Z3 Solution Window Blanket

Pros: Works much better than the BMW window blanket. On new cars it will prevent formation of the dreaded wave. On older cars it helps prolong rear window life.
Cons: Slightly bulkier than the BMW version. Not free.
Cost: $37.95 from Z3Solution

This article reviews the Z3 Solution alternative to the free BMW window blanket. The Z3 Solution product has been designed to minimize or eliminate the dreaded “wave” whcih forms when you leave the top down on your Z3. It does this by providing extra padding in critical areas. The blanket sells for $37.95 from Z3 Solution.

I’ll preface this article with a couple of comments:

* If you are leasing your Z3 and you plan on turning it back in, this article is probably not for you.

* If you plan on keeping your Z3 for a couple of years and are worried about it looking good, especially for resale, this is one of the products you should seriously consider.

The picture above shows two window-blankets. The one of the top is the Z3 Solution version, The one on the bottom is the standard BMW version. They are both made of just about the same type of flannel material, the BMW version is gray, the Z3 Solution version is beige. You can see from the picture that the Z3 Solution version is a bit smaller than the BMW version. There is one critical difference between the two of them: The blanket on the top can prevent the dreaded “wave” in the Z3 plastic windows.

The wave is the effect you see when you put your top down for an extended period of time. When you put the roof back up there is a slight wave which goes horizontally across the window. It’s caused by one of the roof supports hitting the window and creating pressure. Since the Z3 first came out, people have been trying to get rid of the wave by stuffing various things into the fold of the roof. There used to be round pillows you could buy and many people also used pipe insullation material in an attempt to get rid of the wave. None of these approaches worked very well.

Keith, of Z3 Solution, studied the folding of his roof and determined that many of the earlier attempts to combat the wave were really addressing the wrong part of the window. The actual culprit is not the place where the window folds, instead he determined that the second support from the back actually rubs along the window with a lot of pressure creating both the wave and the associated scratch marks.

Keith determined that some padding in the window blanket would be the perfect way to protect the window from the damage caused by the roof support. The problem was that padding the whole thing would mean that the blanket would be bulky in areas where the bulk wasn’t needed. The first think Keith did was to cut down the size of the blanket to just the critical window area. In this way the padded blanket places no extra strain on the roof which might lead to premature wear. The next thing was to pad only the lower two thirds of the blanket, eliminating the bulk at the critical bend in the window.

Keith was also concerned about the quality of the unit. He tested out various materials to simulate the BMW quality. The result is a product which might have come from BMW. Keith uses the same quality fabric, the same connectors and the same quality of fit and finish as the BMW unit. The only obvious difference is the longer loops on the BMW I mentioned that the longer loops and slightly shorter elastics on the BMW model do make it easier to handle and Keith said he would look into addressing this in production versions of the blanket. I have a ’97 2.8 with a hard top. In the fall I had the soft-top completely replaced by BMW, so I got a new window. The window has spent the winter crushed under the hard top, so when I took the top off for the spring I had a significant wave. Keith told me that the Z3 Solution blanket will not remove the wave, but it would keep newer cars from acquiring one. Based on experience, I have found if you hit the window with a hairdryer it will straighten out the plastic.

In several weeks of use, the blanket has practically eliminated the wave from my window. I’m very impressed and would recommend this highly to anyone who intends on keeping their car for a while. Using the Z3 Solution window blanket will definately prolong the life of your rear window and give you a much clearer view. With window replacement running anywhere from $150 and up, the $37.95 Z3 Solution Blanket seems like cheap insurance against a hefty repair bill.

Install VDO Oil Pressure Gauge in BMW Z3 M Coupe or M Roadster

The BMW M coupe comes with a warning light for oil pressure, as well as an oil temperature gauge in the center console. I’d like to know if my oil pressure drops below normal without waiting for the oil warning light to come on at 7 PSI, so I decided to install a VDO oil pressure gauge. This project involves interior trim removal and modification, wiring, and replacement of the oil sender (this last one requires you to drain the oil, so you might as well schedule this project when it’s time for an oil/filter change). As usual, Ron Stygar was a big help on this project. Thanks, Ron! His original post in the bimmer.org archives is here.

Parts Selection

The oil pressure gauge that almost matches the existing coupe gauges is a VDO Vision gauge. I say “almost” because standard Vision gauges come in all black, but the gauges in the coupe’s center console are chrome ringed. If you don’t care about the chrome you can buy a Vision gauge anywhere, but to match the existing gauges I went to Jon Maddux at LeatherZ (www.leatherz.com). Jon sells the 0-80 PSI oil pressure gauge ($79.00) that you need for the coupe, and supplies various colored bulb covers. The orange cover makes the gauge light a very close color match to the existing gauges. For this job you’ll also replace the stock sender with a VDO dual sender with angled mounting adapter that provides both the warning light and pressure reading, and Jon offers these too ($67.00). You’ll be running four wires for the electrical connections – one for power, one for dimming power, one for ground, and one for the sender. I purchased four 10-foot lengths of stranded wire in various colors and this was more than enough length. You need #14 wire for the sender wire to give the circuit the correct impedance; the other wires can be smaller gauge. You’ll also need four crimp-on female wire connectors to make the connections to the gauge and two crimp-on O connectors for the sender connections.

Some coupe owners choose to put their oil pressure gauges in the center console, replacing the analog clock. I didn’t want to give up the clock so opted to put the gauge on the A-pillar. The gauge mounts to the A-pillar, or more accurately to the A-pillar trim cover, in a plastic housing called a “pod”. I bought a single gauge A-pillar pod from egauges (www.egauges.com), part # 240-347 ($31.13). They also sell a dual pod in case you want to add a second gauge such as outside temperature.

Getting Started

NOTE: all directions (forward/rear, left/right) are in reference to the driver’s seated position.

Place the pod on the A pillar trim cover and slide it up or down until you get it approximately where you want it. Mark the location of the pod on the trim cover, then remove the cover by wedging your fingertips between it and the windshield and pulling it away from the windshield. The trim cover is held onto the A-pillar with two snap-in connectors. Once the connectors pop loose, slide the bottom edge of the trim cover out from the crevice formed by the A-pillar and the dash.

Cut a hole (I used a Dremel tool with a carbide abrasive tip) in the A pillar trim cover corresponding to the opening in back of the pod.

This hole is used to route wires and to give you access to the back of the gauge for changing the bulb. If your gauge ended up right over one of the trim cover’s snap-in connectors, you may have to adjust the pod position slightly.

Insert the gauge into the pod, orient it so that it will be straight as viewed from the driver’s position, and secure it by screwing the gauge nut onto the back.

To mount the pod to the trim cover, I drilled pilot holes and used the supplied plastic ribbed pins (screws).


For power, dimming power, and ground wires, you need a sufficient length of wire to run from the gauge to the footwell area. For the sender wire, you need enough wire to run from the gauge to the footwell area, through the firewall, and on to the front of the engine compartment. Leave plenty of extra length on the wires at this point. Terminate one end of the wires with the crimp-on female wire connectors and, using the instructions with the gauge, mount each wire to the proper connector on the back of the gauge. Tape the wires to the back of the A pillar trim cover to keep them in place. Note which color wire you used for each connection.

Disconnect the battery before proceeding!

You’ll need to remove the lower dash panel just above the pedals, loosen or remove the upper dash panel under the steering wheel, and remove the driver’s kick panel with dead pedal.

Run the wires from the back of the gauge through the crack at the bottom of the A-pillar.

They will come out at the left bottom of the dash.

Re-install the trim cover/pod assembly onto the A-pillar.

Editors Note: The silver metal part with the messy looking ends is an interesting safety feature. Somewhat like a pillow, it’s a soft/thin metal with foam filling. Designed to protect your knees in an accident.

Leave some wire slack under the upper dash panel in case you need to remove the trim cover at some later date. Continue routing the wires down into the footwell area. Locate a violet/any color wire for power, and a gray/red wire for dimming power, from the existing wires in the footwell. You will probably have to release wire bundles by cutting wire ties in order to locate the colors you need. The dimming power wire allows you to control the lighting level of your new gauge by twisting the headlight button, the same way you adjust the other instrumentation.

Cut off any excess on your power and dimming power wires and splice them into the selected wires. I soldered the splices and coated them with some Star Brite liquid electrical tape. Connect the ground wire to the grounding nut, forward of the kick panel speaker. (Ground wires are solid brown in the coupe.)

Resecure all wires with wire ties. You can do a power and dimming test at this point by reconnecting the battery; just don’t forget to disconnect it again!

OK, three wires down and one to go! Take the lid off the fuse box (left rear of engine compartment) then unscrew the four #10 torx screws that hold the fuse box onto the wiring box below it. The right rear screw is somewhat obscured by the hood release cable. Just push the cable out of the way enough to loosen the screw. Disconnect the two black wire junction pods, the large red wire, and the green connector that are fastened to the right side of the fuse box and lift up that side of the box.

This will give you sufficient access to wiring box so you can see and grab the sender wire as you feed it through. You’ll see where the main wiring bundle comes through the firewall and into the wiring box. You can try to get your sender wire through the same hole but it’s already pretty well jammed with wires, so I just drilled a small hole nearby and ran the sender wire through it. Drill another hole in the right side of the wiring box; the sender wire exits the wiring box through this hole. Put a dab of silicon sealer on the hole to keep nasties out of your wiring box, and then reassemble the fuse box.

Route the sender wire along the back of the engine compartment, underneath the intake manifold, and to the oil filter, attaching it to the existing wire looms with wire ties.

Sender Replacement

Now it’s time to drain your oil and remove the old filter insert. Remove the air intake box to allow room to reach the oil sender. Unscrew the old sender from just below the oil filter and cut the wire attached to it, leaving as much length as possible. Terminate it, and the new sender wire, with O-connectors.

Mount the new sender to the angle adapter. Hand-tighten the sender to the adapter until snug but don’t over-tighten. The sender has tapered threads that do not require excessive torque to achieve a good seal. Align the sender so that the connector posts on the top are perpendicular to the engine-mounting hole on the adapter. Install the adapter/sender assembly in place of the old sender. Caution – improper installation of the oil adapter can damage your engine and cause oil leaks. Tighten the adapter bolt to 35-40 NM.

Connect the old (alarm) wire and the new (pressure) wire to the correct posts as marked on the top of the sender.

Finishing Up

Replace your filter insert and oil, reconnect your battery, start your car, and check out your new gauge. Under normal operation you’ll see a range of around 15 PSI at idle to 58 PSI. Assuming everything works, replace your interior panels, and you’re done!

BMW Side Impact Protection

At BMW factory in South Carolina there is a Z3 Safety Shell Exhibit that shows off some of the design and technology BMW is using to make these cars as safe as possible. One of the improvements they are especially proud of is the yellow bar you see running horizontally across the door.

It looks simple enough but this bar is designed to protect the occupant by spreading the impact in front of and behind the driver. At the exhibit we were told that this could easily make the difference between walking away from an accident or not.

Okay forget marketing hype, Mike Dwyer saw this device work in real life. “I had someone run a red light and hit me directly on the drivers door at about 35mph. Only a few minor nicks for me, but the M roadster had the back left wheel tweeked and the total bill was almost $12k”

Looking at this picture you can see that the door was the impact zone. But notice the raised ridge (and picture that yellow bar from the safety shell exhibit).

Cleaning the Conforti Air Intake System

I’m a big fan of the Conforti Air Intake System, since installation the unit has not given me any trouble and has offered great performance (plus it sounds good). But the time had come to clean the filter. Thankfully cleaning this air intake is nowhere near as involved as cleaning the dinan air intake.

I simply unscrewed the bracket around the filter and then gave the filter a light tug. Once removed, I beat the dust off the filter with my hand then used water to flush it clean. I let it sit awhile to dry, then sprayed some more of that dust catching spray that came with the Conforti kit on the filter and reinstalled it. Later I was informed that soap and water is the recommended cleaning method.

While the filter was drying I looked at the area under the filer, there was a lot of sand and debris in there so I used a shop vac to clean up the area. Once everything was back together I went for a drive to see how much more power I could feel…. couldn’t tell a bit of difference, oh well cleaner is better anyway.

Retrofitting BMW Roll Hoops

Pros: Upgrades both safety and image of pre-98 Z3’s to 98+ standards. Added protection in the event of rollover. Creates framework for additional accessories, like the windblocker.
Cons: Long, involved procedure. Plenty of opportunity to break stuff. Relatively high retrofit cost for what was a no-cost upgrade to the ’98s.
Cost: $633 ~ $840 (not including installation)

If your BMW Z3 does not have rollhoops it may be possible to retrofit them into your vehicle. BMW has an upgrade kit, but it can only be used on Z3s built on or after 1/97. Specifically 1.9 VIN LB83105 and later; 2.8 VIN LC01377 and later. No earlier production will work (and remember — some “1997” cars were actually built in 1996).

There is no external indication of this. The cars made in 1996 and in 1997 look the same. However, the designers clearly thought that the car needed rollhoops and tried to plan for it, even though the hoops were not ready in 1996 and 1997. It looks like some kind of manufacturing error led to the release of the ’96 cars without the hoop supports, but in ’97 they had (at least) started to install the critical braces. In ’98 the hoops became a factory installed option, standard in the US, optional in Europe and other parts of the world.

(Editors Note: Another rumor was that BMW Legal held up the release of the roll hoops, but manufacturing had already made the design changes. So just the hoops themselves with removed from the scheduled production.)

If your car meets the VIN requirements, it means it can be retrofitted. When you order the kit, you will receive new hoops and a set of instructions. Unfortunately, there are a couple of problems:

First, the kit is not complete, there are some additional parts required. The list of parts varies depending on the type of car you have (color and rear-console configuration).

Second, the instructions with the kit do not cover the install for a Harmon Kardon equipped vehicle.

This article seeks to address these shortcomings and to provide the potential hoop-installer with enough information to make the decision to install themselves or to have BMW do the job.

General Instructions

BMW will generally quote about 5 hours of time to do the install. Most BMW dealers charge around $75 per hour. A competent do-it-yourselfer should plan on about 8 to 10 hours. Although it’s not a technically complex procedure, there are lots of steps and some fabrication required. In general, anyone handy with a wrench and power drill can probably do it. The only “special” requirements are for the special tools required: TORX bits, metric torque wrench, Hex keys, dremal tool or power drill and screwdrivers.

Although your car can be driven during this procedure, it will likely have a lot of small parts loose, so it’s not advisable. Therefore you should plan ahead and have all the parts and tools ready beforehand.

Before you start, clean the rear window. Once the hoops are on it will be a lot harder to do so you want to do a really good job. In addition, have a couple of towels around to protect the window as you work. Generally speaking, the top is down for most of the install, so only a small part of the window is exposed.

As with all procedures read all the instructions first. Print these instructions beforehand. You’ll want them close by as you start to take your car apart. The hoop kit will come with instructions as well, but they will be in German with an English transation in the back. It’s much easier to follow these instructions in English (unless, of course, you speak German 😉

As you remove small parts, tape them to the instruction sheet or tape them near where they came from (whichever is easier for you). There are lots of different sizes and shapes and they are easily confused.

When you are done, sweep up before moving the car, that way you will not run over an errant screw and ruin a $200 tire.

BMW only wrote up instructions for cars with the “Storage Compartment” option. They did, however, provide parts for retrofit of HK subwoofer cars, but with no additional instructions. Since the majority of the instructions in this article come directly from the BMW english instructions shipped with the kit, they are intended for the “Storage Compartment” installation, but can generally be used with the HK subwoofer. I have added notes where the Harmon Kardon installation differs. These are identified by “HK NOTE:”. There are no instructions for the Nokia subwoofer and no one I have ever talked to has attempted to retrofit hoops to a Nokia-equipped car.


The part number for the main kit is 54-61-9-408-817. BMW list price is $640.00, but you can find them at a discounted cost of $430 from some internet-friendly BMW parts departments. You can also try your local BMW dealer who will generally give BMWCCA members a discount on parts (15 or 20%).

In addition to the kit you also need to order a replacement set of plastic covers for the rear storage/subwoofer area:

The actual part numbers will differ depending on the color of your interior and your rear compartment type (Storage or HK Sub). See the following table for the list of parts you’ll need to order in addition to the hoop kit:

Harmon Kardon Subwoofer Storage compartment

Beige interior

51-16-8-407-986 $59.41

51-43-8-407-167 $28.09

51-43-8-407-168 $28.09

51-43-8-407-173 $4.45

51-43-8-407-174 $4.45

65-10-8-407-995 $8.57

65-10-8-407-996 $8.57

Total: $141.63

51-16-8-407-179 $10.01

51-16-8-407-180 $10.01

51-16-8-407-239 $88.72

51-43-8-407-167 $28.09

51-43-8-407-168 $28.09

51-43-8-407-173 $4.45

51-43-8-407-174 $4.45

Total: $173.82

Black interior

51-16-8-407-985 $59.41

51-43-8-407-165 $28.09

51-43-8-407-166 $28.09

51-43-8-407-171 $4.45

51-43-8-407-172 $4.45

65-10-8-407-995 $8.57

65-10-8-407-996 $8.57

Total: $141.63

51-16-8-407-177 $10.01

51-16-8-407-178 $10.01

51-16-8-407-238 $88.72

51-43-8-407-165 $28.09

51-43-8-407-166 $28.09

51-43-8-407-171 $4.45

51-43-8-407-172 $4.45

Total: $173.82

The kit for the subwoofer will only work with the Harmon Kardon subwoofer. There is no kit available for Z3s with the “regular” Nokia subwoofer.

HK Note: If you’re doing HK, you’ll also need six 6×20 (6 mm x 1mm) pan-head screws which can be bought from Home Depot or your local hardware supply.

You may also want to order a number of small caps for the screw heads:

Black Screw Cap: 51 161 949 793

Beige Screw Cap: 51 168 398 920

You will be removing about 6 of them and will, more than likely, destroy most of them in the process.

You should also order a gasket: 51 168 399 072

This part fits in between the new rear covers. Although you do get one gasket with it, the extras will allow you to seal up the area between the covers.

Thre are two extra projects which are easy to perform as part of this install. For them you will need 4 size “00” washers, a small strip of velcro “loop-side” and a piece of foam padding approximately 12 x 12 inches large and 1/4 inch thick. These projects are not absolutely necessary to do for the hoop install, but since you will have the car apart, it’s a good time to do it.

Although it’s beyond the scope of this article, hoop-install is also a perfect time to replace your rear speakers.

54-61-9-408-817 Kit Contents

HK Note: You will need to modify part H. You can toss parts I and J – you won’t need them.

Extra Parts:

You should have the following “Extra parts”:

m. seatbelt tower covers (L & R)

n. inner covers (L & R)

o. center cover

p. brackets (2x)

q. gasket set

r. pan head screws (from Home Depot – HK only) (6x)


Note: In the instructions, the word “spanner” means “wrench”. The instructions were clearly written by Germans for the UK market.

You’ll also need a socket set (with philips screwdriver bits for hard to reach places) and a saw or a dremal tool if you are doing the HK install.

Important Safety Tip: When sticking tools down inside the car, be sure they are tightly attached. When I did this, in the final tightening of the hoops, I dropped a TORX attachment down into the opening and had to take the whole thing apart. Don’t let this happen to you. Suggestion: tape your tools together.

Phase I – Lay out your parts

Lay out a sheet or large towel and place all your parts on it. Take inventory and make sure you have everything:

Phase II – Strip Your Car Naked

In order to install the hoops, you will need to remove a large number of parts from the car. Before starting, lay down a sheet, or large towel where you will place the parts you remove. Be sure to label each part as you remove it, this will help when you go to put it back together.

Important Safety Tip: You will need to have the top folded down. The rear window will be exposed and will be very close to where you are working. You should take extra care to cover the window with a towel to protect it.

Note: Those darn screw covers! They are easy to tear. I’ve used a strong paper clip to remove them, but you are better off just buying a bunch before you start and not worrying about how badly you screw them up in the removal process. There is a small hole along the edge, you can grasp onto this hole and pull. Usually the cover just shreds at this point.

Note that you just gently lifting up the console enough to get at the screws. Be careful, it’s still attached at the front and you can damage it if you pull too much.

Hint: raise the roof at this point. It gives you a little more room to work in for the next step and there’s less danger of hurting the rear window as you remove the screws behind the storage box.

Now lower the roof.

HK Note: In order to gain access to the HK compartment, pull up on the cover, hard, from the front center area. It is hinged at the back and should just fold back. Don’t worry about breaking it – you’re just going to throw it away.

Next remove the grill for the HK “speaker”. You can do this by grasping the sides and pulling towards you. Remove your “snorkel” (this is the part which moves the sounds from the HK down to the grill) by pulling it outwards through the grill opening. Next, remove the HK subwoofer by unscrewing it from it’s mounts (4 screws) and unhooking it from the wiring harness. (for more information see this article from //MZ3.NET)

The instructions “Undo the clips(1) on the rear floor covering” refers to the plastic piece behind the seats. The diagram shows you looking from the drivers side towards the passenger seat belt. Unfortunately, in order to get this part to move as much as you need to, you also have to undo the sill strip at the bottom of the door. I just pulled up (HARD) and it came off. While you’re pulling it feels like you’re going to break it, but it’s pretty resilient. There’s probably a better way to do it. I suspect if you pull up and “reverse curl” the sil, the part will release from the fasteners. However on mine, 2 fasteners pulled out, still attached on both sides. This was not a big deal, I simply removed the third, and inserted it into the sil on reinstallation.

Phase III – Install the Hoops

OK, you now should have a naked car. The next step is to start installing the hoop supports and the hoops themselves.

HK Note: Before starting, attach your extra “HK part P” to “Part B” (see the parts list) with the screws you got from Home Depot. This bracket will support your HK subwoofer later on in the install.

HK Note: Skip this step, you don’t need the hinge

HK Note: Skip this step (F 36 54 059)- don’t remove the old silver “hinge supports” – you need them to back up the Tenax fasteners.

HK Note: you’ll need to “modify” the box which fits inside the console by cutting off the ends as indicated by the red line in picture. You don’t use the center box, but you will need the “ears” (the ends). Keep as much of the ends as will allow you to preserve the slots (these are used for the trim parts to secure with).

HK Note: Skip this step (F36 54 060). You will not need the hinges. Look at the next step, but skip down to the next HK Note instructions.

HK Note: Secure the side parts (highlighted in red in the picture) as indicated in the instructions. Next put the HK Subwoofer back in, reconnecting it to the wiring harness. The HK Cover does not use the hinges. Instead, it is secured by small tabs in the back. The new top will need to be inserted vertically. Before doing so, you must modify the metal plate (highlighted in yellow)

You’ll need to drill a couple new holes in the plate which secures the front of the cover. The problem is that the “studs” in the cover don’t line up the way the ones in the old cover do. I put some masking tape onto the cover and “pushed” an indentation into it to see where the holes should go. I then used my demal to make the holes. Careful: I made a mistake and made the holes a little too large, so I to buy a new part and start all over.

You also need to enlarge the existing holes to make room for some new screws on the cover where the old studs went. The new top then just “drops in”. You need to be careful to place it down vertically or you might break the small plastic parts which hold it on.

Phase IV Additional Hints and Tips

Now that you’ve taken most of the back console apart, you can take the opportunity to improve things a little more. There are two major areas in the rear console which can be improved with a little extra work:

– Eliminate the buzz from the HK subwoofer

– Improve the Tenax Fasteners (these are the little round knobby bits you fasten your boot cover to)

First wrap your subwoofer snorkel in some kind of foam insulation when you are reinstalling it. This prevents it from vibrating. I used some backing foam, but you can find this stuff at any harware store in the insulation section.

Next, get some velcro. You’ll just need the “fuzzy” (loop) side. Cut it into small (1/4 inch) strips. Look for wear-points on the inside of the grill. If you can’t find any, simply place the velcro near each corner. If you do find a wear point, place the velcro over it. This prevents the grill from buzzing.

While you’ve got the Tenax fasteners off, do the “Robert trick” – put a couple of “00 washers” behind them to stick them out more and make the boot easier to fasten.

Phase V Cleanup

Parts-is-parts… and if you did the HK install, you’ll have a bunch of extras:

Don’t worry about it. The HK install does not require these parts as they are designed to support the storage compartment install.

You did it!

Congratulations! You’ve now got a safer, cooler looking car.

Now that you’ve got rollhoops you can also avail yourself to another nice feature: The Wind Blocker. There are two versions available, a clear, plexiglas version from Z-Aids and a mesh version form BMW (Part # 82-15-9-408-546). This article from MZ3.net provides a pretty good comparison of the two products. I personally own both of them and enjoy using the clear screen in the spring and fall, reserving the mesh screen for the summer (because you can fold it down if you want the “wind through your hair” effect).

Overall, I’m very pleased with my rollhoops. Hope you are too!

2.8 SuperTrapp Exhaust

Subject: Muffler system upgrade for a 2000 2.8 Z3 Roadster
Cost: $150 for the exhaust plus installation (approx $75), I just checked the website and the price increased to $160.
Good: Customizable sound & performance, low cost AND lightweight
Bad: Non-that I am aware of at this time.

Why do this: As the immortal Tim Allen said “MORE POWER”. One of the first things I did to get more power out of my 2.8 was to Fogg the cold air intake (CAI). Even though Shawn never did a 2000 2.8, I took his ideas and suggestions from both his instruction on the 1.9 and from communications with the immortal himself and I was able to modify my CAI to work similar to his.

Of course this was not enough. So the hunt was on for a more affordable power upgrades. So I started looking into exhaust system replacements. I looked at every type possible, even asking about replacing the exhaust manifold and/or catalytic converter, not without screwing up my emissions & computer. So I concentrated my search to muffler replacement only. I looked at Bola, Dinan, Supersprint, etc. I searched for all types of information (horsepower increase, cost, material type, etc.) that would help me decide what muffler to purchase. I read all the articles from the MZ3 website on exhaust/muffler systems.

To my surprise, I found that all the stainless steel mufflers’ costs were in excess of $300 to $600!!!! Not including installation. Plus I was not convinced that the performance versus cost ratio was worth the money spent. I then remembered about the SuperTrapp system. They were primary an aftermarket motorcycle muffler. But, I saw them on cars in the past, about the late 70s. Plus I knew that they made systems that were stainless steel and lightweight. So the hunt was on.

First: I found their limited website http://www.supertrapp.com/default/atv_splash.htm not a great site to see what was available. But it did explain on how their system works.

Second: I found a supplier (there were not many in my area): http://www.racesearch.com, Part number: 543-2519, http://www.racesearch.com/CGI/mhp?mode=sbpn&pn=543-2519

Third: I found the one I wanted Stainless steel 5″, now granted if you called SuperTrapp & view the Z3 Coupe message board, they recommend that I use a 4″ system for horsepower up to 250 Hp. The 5″ system is rated up to 400 Hp. The reasons for the 5″ is simple with the wider inner diameter, the exhaust gasses would flow easier, less noisy and the 5″ outer diameter fills the factory muffler exhaust cutout nicer.

Arrow points to the location where the stock exhaust tube was cutWhen I had my muffler installed I had the installer hack off the original muffler and it’s supply piping back to the rear axle. If you look at the picture, you will see that the bend to the muffler has been reduced. He then made some custom hangers to hang the muffler at the stock points. Due to the heat generated from the exhaust gasses and the many discussions on the message board on melted bumper fascias due to the muffler. I instructed the installer to have the muffler hang a little lower and poke out more than normal. Giving it less of a chance of the muffler from melting the bumper fascia.

What is with the metal disks and cover???? The SuperTrapp muffler is basically a “glass pack”, where you have an inner tube that has holes and an outer tube that has insulation between the two tubes. Since there is no bends or baffles within the muffler, the gasses are unrestricted to flow toward the end of the pipe. Now the glass pack system has been around for a long time, if you had a hotrod or muscle car, you will know what I mean. Now for the metal disks and cover. The disks that you see on the side of the muffler are really spacers that have been stamped to allow the exhaust gasses to pass between two spacers. The metal cap is to help tune the performance of the muffler and car. Now the easiest way to explain this is to imagine that you have a large bucket with some holes in it. Now fill the bucket up with water, you will see that the water takes a long time to empty out. Now add more holes to the bucket and add water, you will now see that the water will empty out quicker than before. So the more holes you add the faster the water exits. Now there is more to the SuperTrapp system, which deals with vanturies that help pull the exhaust gases from the car. View the SuperTrapp website for more information.

Basically this is how this works with the car: The less spacers you install on the muffler, will produce more backpressure on to the system. Thus, increasing your torque, decreasing overall horsepower and a more quiet sound. With (6) spacers, the noise was a similar to my stock system. The more spacers you install on the muffler, it will reduce backpressure. Thus, decreasing your torque, increasing overall horsepower and a more robust sound. I ran both (12), (18) & (24-max) spacers. I normally run (24) spacers as a daily driver. Which is has a nice growl during idle and a cool roar during hard acceleration plus, I have had no complaints from my neighbors. I did try the system with NO spacers and it was too loud for normal driving.

I have raced my new exhaust with only (12) and no spacers, only to find that no spacers worked best. I will try my (24) spacer setup to see how it fares. Since the installation, I have not conducted a horsepower comparison, my fault. It will be hard to see if my new muffler has done anything, because I have done a ton of things to get this car quicker than stock. Check out my website for details: http://www.z3power.net

Summery: I am happy with the purchase of this muffler and I would do it again. In addition, if I did not have any performance gains in torque or horsepower, I have reduced the overall weight of the car. Which is always a good thing for our heavy cars.

Dinan ///M Air Intake

The ///M engine can benefit from additional air (mass) intake, however the Dinan design (specifically for the M roadster and M coupe) concerns me. Look at the picture below, the air filter is exposed in the lower air intake (front bumper). While this may provide additional performance I really question the long term effects. The K&N filter is rather durable, but what happens when it gets wet. I’ve heard a report of a check engine light coming on after a car wash. I also look at the amount of rock chips this section of my bumper has picked up and wonder how long a paper filter could last against this kind of impact abuse.

For these reasons I would not recommend the Dinan intake unless it was only for Autocrossing or Track use, even under those circumstances I question if the Dinan design has any advantage over the ECIS or Jim C design.

Update: I have been informed “Dinan is now shipping (for free) filter covers, a la K&N condoms, which are supposed to solve these issues”. I think this shows great customer service and reminds everyone why Dinan is such a popular company to do business with.