Remus Exhaust for the M Roadster

Pros: Better Performance, Improved (Lower) Sound, Easy Installation
Cons: Expensive, Not Stainless Steel
Cost: $801 (includes shipping) from MG Racing

The stock exhaust on the M roadster is pretty good, however I was always wanting a little more rumble and sound. Previously I owned a 1.9 Z3 and had upgraded its exhaust using the Remus brand. I was very pleased with the results and when the itch to upgrade the M roadster exhaust hit me I decided to try the Remus M exhaust.

After placing my order and waiting a week the doorbell finally rang. It was the UPS delivery man with two very large boxes for me. Just like the 1.9 exhaust the new Remus exhaust was packaged without any padding inside the cardboard box, one of the boxes was fairly chewed up the other one only had slight damage. I didn’t notice it at the time, but one of the supports on the passenger side exhaust had been slightly bent. Let me just get this complaint out of the way, would it kill them to package these things in Styrofoam or something. Just like the 1.9 exhaust this one had become damaged (support rod bent) in shipping, the damage is easily repairable but it sure would be nice if I didn’t have too.

The good news was that the chrome tips on each exhaust arrived unharmed. Measuring the exhaust tips I found that the inside diameter was the same as the stock exhaust, but the thickness of the exhaust tip was 5mm bigger making the overall outside diameter of the Remus exhaust 10mm bigger than the stock exhaust. On the top of each chrome tip is an engraved Remus name logo. Once the exhaust is installed both the name and the logo can be seen. The shipping weight on the Remus exhaust was 70lbs total (35 per side), while I have not weighed the stock exhaust myself I remember BMW saying it weighed roughly 100lbs.

Installation

The hardest and longest part of the installation was the first step, getting both the Z3 and the new exhausts to the installation location was more difficult than I thought it was going to be. There was no way these big things were going to fix in the Z3. They also did not fit in the trunk of my wife’s 318i, luckily I found a way to fit one in the back seat and another in the passenger seat. I ended up having to drive the 318i (carrying the exhausts), then drop off the exhaust, then return home, then drive the M roadster to the shop, install the exhausts, drive the M roadster home, return with the 318i, load up the stock exhausts and them drive them home. I probably spent more time driving cars around than it took to actually install the exhaust.

The actual installation process was very easy, but before I could start I needed to let the exhaust cool off. During the installation process you will be holding some parts of the car (like the muffler) that get quite hot while the car is running.

Once it had cooled down the first step was to remove the stock exhaust. There where 10 bolts in total (5 per side) holding the stock exhausts in place. On each side there are two bolts mounting the exhaust to the catalytic converter (top right), two bolts holding the rear of the exhaust in place (bottom right), and one bolt in the middle (middle right).

I should point out that the exhaust is actually held in place via some rubber hangers that allow the exhaust to slight move and adjust in normal operation. The bolts I’m referring to attach the rubber hangers to the car.

Instead of removing the rubber ring that was holding the middle of the exhaust in place, I decided to remove the bolt that holds the bracket that the rubber ring is mounted on. This made lowering the exhaust a little easier. I started by removing the rear bolts first, then the middle, and then the front. But I had someone holding the rear (muffler) exhaust while I was doing this.

The only part I replaced (at the advice of Larry Nissen – BMW tech) was the ring seal that fit between the cat-back exhaust and the catalytic converter. Larry didn’t think this was “necessary”, but it was possible that a exhaust leak might occur using the old rings, so we decided to replace them just in case.

After one last side by side comparison it was time to install the Remus exhaust. I was quite impressed at how easily and precisely the Remus exhaust fit into place. Starting with the rear bolts first (while someone held the front of the exhaust) the new exhaust was put into position. The first pass the bolts were left loose, a second pass tightened them all down. The only part of the installation that wasn’t smooth was the support that had become bent in shipping. But after a few whacks with a hammer it was bent back into position and the installation was complete.

Once the Remus exhausts were installed I took a look at the exhaust tips to see how centered they were in the cutouts of the rear bumper. I was concerned that an off center exhaust tip might melt some of the rear bumper because I have seen that happen with some aftermarket exhaust. But I was relieved to see that the exhaust tips were perfectly centered in the cutouts. The Remus exhausts really were a direct replacement, practically plug-and-play. They fit precisely in place of the stock exhaust without any modification. But now that they were installed the next question was, “what will this do to the M roadster’s performance?”

Performance

I always liked the Remus exhaust I put on my previous 1.9 Z3, but I regretted not doing “before” and “after” dynos on the car to see how much of a performance gain the aftermarket Remus exhaust gave me. I didn’t make that mistake this time, a “before” dyno was recorded with the M roadster in stock condition after it was broken it (click on the graph for a larger view).

After the installation the car felt quicker and it seemed to run through the upper RPM range faster. In fact I even bounced it off the rev-limiter a few times on accident until I got use to the new tach speed. But all this was just non-scientific (what some people call the “butt-dyno”) data. I knew the car felt quicker but what I needed was a real dyno to prove it. I returned to the same place where I had my M roadster dynoed before to see just how much of a gain the Remus exhaust gave me (click on the graph portion to the right for a full screen view).

What the dyno did was prove what I was feeling, the Remus exhaust boosted the torque across nearly the entire RPM range. The biggest gains were found in the range between 3500 and 5100 with a peak gain of 13 ft/lbs of torque at 3800 RPM. The only exception was the RPM range between 2300 and 2500 which showed no gain. A few skeptics said that an aftermarket exhaust might gain power in one area but then loose it in another. What the dyno showed me was that the Remus exhaust never hurt performance, improved the performance across most of the RPM range, and even smoothed out some of the torque curve where dips in power occurred on the stock dyno.

I was hoping to back up the dyno data with performance timing, so I purchased a GTechPro which measures 0 to 60 and quarter miles times. I took several measurements before the exhaust upgrade and several measurements afterwards. However I don’t think that data can be trusted because what the GTechPro really did was teach me how to drive the car faster. In between the before and after testing I had improved my driving skills enough to make those tests invalid. I also didn’t pay much attention to the temperature variations which might also explain the gains I was seeing. So really the only thing I got out of the timing tests for this article is this fairly cool real video.

Sound

The Remus makes the exhaust note lower and slightly louder, but rather than have me try to describe the sound in words check out the sound files below. You will need the RealPlayer to hear the audio, if you don’t have the RealPlayer the good news is it is free!.

For the following sound recordings two ’98 M roadsters were put side by side. A Hi8 camcorder was used to capture the audio, I was standing about 10 feet behind the two roadsters and did not move between recordings. RealAudio is by no means a crystal clear audio media, but comparing the sound files (Stock vs Remus) is a really good comparison of the real life difference.

Stock M roadster

Remus M roadster

Long Term Update

4/30/99:

I think my initial figures are incorrect, especially after looking at the other exhausts articles and comparing the results. When I initially posted the article I used before and after dynos taken on different days. I think the ODBII adaptation caught me, because if you look at the numbers it would appear that I had a peak gain of 7 ft/lbs, average gain of 5.8 ft/lbs across the entire RPM range, 7.8 ft/lbs gain in the 3k to 5k range (driving range). The 7.8 ft/lbs of additional torque is roughly a 4% gain in power in the highly used 3k to 5k RPM range.

What’s interesting is if you compare Alan and my “after” dynos you see that they are practically identical. How can the Remus give me a 4% gain and the Supersprint give Alan a 2% gain, but we end up at the same numbers? I think the answer is that my original “before” dyno is questionable. What I did to try and “fix” this error was take the two different “before” dynos and combine them by using the high points from each graph. I then used this new line and compared it back to Robert’s original “after” dyno.

Looking at the “fixed” comparison, I think these figures are more correct. Peak gain of 4 ft/lbs, average gain of 2.9 ft/lbs across the entire RPM range, 3.7 ft/lbs gain in the 3k to 5k range (driving range). The 3.7 ft/lbs of additional torque is roughly a 2% gain in power in the highly used 3k to 5k RPM range.

Chrome Lighted Shift Knob

Since you can never have enough chrome in an M Roadster (open to debate, perhaps) I decided to add the BMW chrome gearshift knob. However, if I did that I would loose that cool lighting effect from the stock gearshift knob. I decided to try and make a chrome lighted gearshift knob.

You will need to remove the standard shift knob. Lift the cover up around it (it’s just held in place by small tabs on the side), and find the connectors for the wires leading to the knob. Disconnect these and simply pull straight up on the knob. It’s tight, but it should come off. Be careful not to hit yourself while pulling it up.

The first thing I did was to take apart the stock knob to see how it worked. It’s really just 3 tiny LEDS and a resistor under a knob emblem that let’s light shine through. Since BMW does not sell this emblem as a separate piece, you will need the one from the stock knob. Put your fingernail under the edge and simply pry up. It’s held on by double-sticky tape and should come off easily. Be careful not to scratch either side. Also important, the “silver” look of the numbers is not really paint. It’s some sort of dust that very easily wipes off. Do not get your finger anywhere near it, or you’ve just ruined the emblem.

The next thing you will need is the wire connector off the standard gearshift knob. Cut the wires (but leave some space to work with). I choose to get some nylon connectors from a local electronics store and solder it on the end of the BMW connector. That way I can still take my knob off without dealing with the BMW connector (which is a little big and won’t come off though the hole in the cover that easily).

Now it’s time to work on the chrome knob (which you need to purchase, of course). You need to get the emblem off without scratching the knob itself. The knob itself is covered in some sort of thin film that protects the metal (which is very soft). If you scratch the knob, it will look BAD. So don’t do that *smile*. The emblem is held on by the same double-sticky tape, but lots more or it. The best way I found is to use a dremel and drill directly into the center of the emblem with the dremel screw-like attachment, then yank the emblem off. Remove the remaining double-sticky tape, but save it – you will need it later.

Under the emblem you will find a little hole which is almost the right size. If you were to put the M emblem over this hole, the “R” and the “5” would not light up, because the hole isn’t big enough. Carefully grind the edges away where those two spaces would be (i.e. instead of a round hole, you would create a hole that looked like it had mickey-mouse ears). You don’t need to go very deep, long enough so that light can shine through. Now look at the underside of the knob. Inside you will see a couple horizontal plastic bars that hold the knob in place and keep it from spinning around. Through the center of the knob (in the hole on the top) drill out a vertical line that intersects the horizontal bar. Go all the way through till it’s completely open. You are almost done at this point.

Go back to your car. Figure out where that horizontal bar would go (it’s plainly obvious). Now cut (grind, actually) a small groove down one side of the stick. It doesn’t need to be very big, but you need something to run the wires in. On the stock knob, the wires actually run along the outside of the knob, but with the chrome knob we can’t do that so we need this grove. It won’t affect the functionality at all, there’s still PLENTY of metal left. When I did this, I took a vacuum and left it up close to where I was grinding to keep all the particles from spraying through the inside of my car.

Back to the chrome knob. Take some very small gauge wire (I used the individual strands of a telephone wire) cut two 18″ pieces. One one side, solder an LED to it. I used a jumbo orange LED from radio shack, their part number is 276-206 and the color matches the rest of the car pretty well. On the other end of one of the wires solder a 470 ohm resistor. Then solder on the mating end of the connector that you soldered on the BMW connector.

Go back to the car. Thread the connector attached to the knob through the leather shifter cover, and place the cover back on the car. Now carefully place the chrome knob on the car. Line up the wires in the groove you cut and on the top have the wires come out next to the horizontal bar (i.e. the LED [attached to the wires] still isn’t in it’s final position, it’s sticking out further). If you did everything right, the knob should be in position and on tightly, but if you hold both ends of the wires you can gently slide the LED back and forth. Pull on the wires until the LED is flush in the hole.

Lastly, you need to put a diffuser and the emblem back on. For a diffuser, you can use the white plastic one from the stock shifter, or simply cut a piece of white paper in the appropriate size. Use that double sticky tape you saved earlier to put the emblem back on. Re-connect the wires and put the leather cover back in place, and you are all set!

Another thing to watch out for is to test-fit the emblem into the chrome knob. I’ve had two different knobs, in one the M emblem fit just fine, but in the other I had to slightly grind the emblem down to get it to fit. Also, be careful not to push too hard getting the emblem in place, it CAN crack internally and have ugly white lines running through it. In direct sunlight, the knob can get VERY hot – so you may want a pair of driving gloves. And the wires you use to connect the LED can get damaged very easy, so if you take the knob off again you may want to plan to replace those wires.

All in all, I’m happy with my unique shift knob!

Dual-Stage Radar Sensor

I started with the excellent article on adding a motion sensor to the BMW alarm. I encourage everyone to read that article first, as I’m not going into enough detail to do the whole job. Consider this as a set of “release notes”. Also, I assume both the BMW alarm and the motion sensor have been installed at this point. Read over all of this first, since I make comments like “connect with to power” then later talk about “put a switch in”. It’s better to do this all at once, but easier to explain using several passes at it. Remember: measure twice, cut once, measure again.

Changes desired from the existing article:

I wanted to use a dual-stage sensor, thus the car would “chirp” when someone got too close to it, before setting the alarm off

I wanted to know which stage sensor had been set-off, by visual inspection (i.e. LED)

I wanted a cutoff switch for both the motion sensor, and the outer stage “chirp”

I wanted to have the sensor be easy(er) to adjust [i.e. not have to pull the car apart to adjust the sensitivity]

I purchased a dual-stage sensor from www.autotoys.com. This sensor is basically the same as the one mentioned in the previous article except that it has two stages of detection and comes with a small piezo buzzer to use as the outside “chirp” sound.

The first thing I did was to decide how I was going to wire everything and and measure everything. Based on other articles and talking with various people, I decided to put the sensor in the center dash, between the seats (under the cassette storage area). After removing the cassette storage bin, I was able to use my pocket knife to lengthen the hole already there to be just long enough to slip the sensor in. I put velcro tape on the sensor and the underside of the dash, and attached the sensor there. This had the advantage of making the screw to adjust the sensitivity easily accessible. I just remove the cassette bin (no tools needed), then use a small screwdriver to adjust the sensitivity. Thus, desire #4 was satisfied.

Next, I wanted an LED to show the status of the sensor. The sensor has an LED already attached to it, a bicolor red/green LED. I simply desodder it, sodder in extension wires, and added the LED to the end of those wires. I was able to snake that new cable (I used heat-shrink tubing to hold the wires together) through the gear-shift area (the shift boot cover comes off easy) and into the blank punch-out button area (which the light for the alarm itself and the glass-breakage sensor already were). I drilled another hole, and used one of the radio-shack LED black plastic covers to give it a professional look. It’s a little crowded there, but still looks good. OK, desire #2 is done.

I needed a place to put the buzzer that was going to serve as my outside warning. I decided it needed to go in the engine compartment, since that was the place the siren was, etc. It’s small so it can go anywhere. I choose up by the drivers wheel, inside the engine compartment. I tie-strapped it into place.

Now I had to find a way to get a couple wires into the interior of the car. If you look where the battery used to go in the ’96 model Z3, in the M roadster there is what looks like a bunch of cables doing just that, but they are fully covered and have a rubber grommet around them. I was able to move the rubber grommet just enough to snake the cables through to the interior. They come out just above the kick-panel speaker in the passenger wheel-well.

OK, this part is from memory (so PLEASE test all your connections before listening to me). I believe I hooked the red wire on the buzzer to the unswitched power supplied to the alarm. The black wire (ground) from the buzzer was attached to the green trigger wire on the motion sensor. I believe when motion is detected, this wire to connected to ground, thus the buzzer goes off.

Now I wanted to install cutoff switches, so I needed a good hidden location. I found one beneath the glove compartment. There is a piece of plastic that goes out from the firewall at a 90 degree angle, that’s what I used. It’s the piece of plastic that has the 2 or 3 plastic turn-screws to keep it on. In the center I was able to cut the holes for the switches themselves. I picked up a couple neat-looking blue auto-switches from a local electronics place and test-fitted them there. Make sure when the switches are in the plastic that there will be enough space to put the piece back on. Some of the tolerances were pretty tight. Now, cut the wire that supplies power to the motion sensor and connect one side to one terminal on one of the switches and the other side of the wire to one of the other terminals. Do the same thing for the cutoff for the “chirping” buzzer. OK, item #3 on my list is done.

OK, one last problem. When the car is running, so was the motion sensor. This has two side effects: the green light keeps going off indicating movement and the outside buzzer is also going off! While driving! This was unacceptable to me.

The solution was to use a relay, like is often used for fog lights and such. Make sure you get a real relay that has both an “87” and “87a” connector (the first one I bought said it had both, but really only had two “87” connections). Basically, you hook power up to the relay and based on whether power is applied to a third connector (or not), passes or does not pass power. The difference between “87” and “87a” is that they are the inverse of each other (one has power when the other doesn’t, and vice-versa).

I don’t remember the details (I’m a computer guy, not an EE), but it should be easy to understand based on the diagrams with the relay. Basically, hook ground an unswitch power directly to the relay. Then the terminal that determines whether power should run or not is hooked to the car’s “switched” power (the violet wire with a white stripe in the alarm harness). Then the terminal that has power with the terminal just mentioned does not have power should be feeding power to the motion sensor. Now, the motion sensor (and the outside buzzer) are only on when the car is switched off!

That’s it!

If you have any questions, you can email me at caslis@netcom.com

Used Airbags

I hope you never have to see your Z3 in this condition, but below are some pictures of a Z3 after its airbags had been deployed. I’m not sure whose Z3 this is; it was parked at a BMW dealership.

This first picture shows the passenger side airbag. It is much larger than I expected it to be. The fabric looks like a thick, almost canvas like surface.

The driver’s side airbag was much smaller, but it looked like someone has pushed part of the bag back into the steering wheel. Looking around the cabin, I expected to see some white powder, but the interior was clean.

What surprised me the most was how little damage there was to the front bumper. I expected to see a lot more damage if the impact was enough to set off the airbags. It is my understanding that the Z3 knows if you are wearing your seat belts or not and will deploy the airbags in a lesser impact if you are not wearing your seat belt. I don’t really know any details, just observing how little damage there was to the front bumper.

1998 Best Owner Designed Product Award

In choosing the nominations for this award MZ3.Net decided that each nominated product needed to be a unique addition and/or upgrade for the BMW Z3. The product must be created by a Z3 owner and marketed by that owner to other Z3 owners. Most importantly, the product needed to receive positive feedback from the general Z3 audience.

Using these guidelines, MZ3.Net nominated six products and then asked its readers the following question…. “There have been several third party accessories made for the BMW Z3. What in your opinion is the best BMW Z3 owner designed product of the year?”.

The six nominations were….

Kathy’s Z Window Pillow, which helped keep the rear plastic window from getting crease/fold marks.

Greg’s Chrome Kidney grills, which added an additional flash of chrome to the vertical slats in the front kidney grill.

Keith’s Atomic Cupholder, initially cut from PVC pipe, the design was so good it was later sold to HMS motorsport.

Bill’s Bike Rack, because only a custom job would work with the Z3 bumper.

Carter’s Roadster Tonneau, which quickly covers the Z3 interior while leaving the top down.

Keith’s StoneGuards, which were thin magnetic strips designed to protect the rear fender flares from rock chips.

Voting went on for several months and ended on December 31, 1998. While all the nominations were outstanding products, in the end the voting revealed a clear winner.

StoneGuards 95(32%)
Roadster Tonneau 71(24%)
Chrome Kidney Grills 48(16%)
Atomic Cupholder 29(9%)
Z Window Pillow 27(9%)
Bike Rack 21(7%)

///MZ3.Net would like to thank all its readers for participating in the voting and congratulate all the nominations. The 1998 Best Owner Designed Product Award to Keith Shelburn for his Magnetic Stone Guards.