Exhaust System for the Rockster

[ccRider91351]

Hey to all of my Rockster bros. I want to put a new exhaust system on the Rockster. I recently put on a new akrapovic slip. It works great, it increased the horsepower and it's louder than the stock. Love the results. However, I have come to learn that if I had the entire system, I would not only get more hp, but increase the gas milage. akrapovic does not sell the whole system (exhaust) for the Rockster. Can anyone recommend a system for the Rockster. I need it loud because I use the Rockster to commute in this heavy L.A. traffic. Thanks in advance.

[harrisphil]

any Cat replacement Y piece will work better than having a Cat there and they should all work with the silencer that you have got

[Sunfire]

I've been looking at mufflers for my Rockster, and I would like to use the stock heat shield. From what I've learned, the only exhaust that makes use of the stock heat shield is the Akrapovic slip-on (http://www.akrapovic.com/nc/motorcycle- ... ster-2003/).

Is this the one you purchased? If yes, at 92dB, is it very loud? I know that loudness is perceived differently by everyone, but I was just wondering if it would attract too much police attention.

Paul

[jfslater98]

If you still have the catalytic converter, don't worry, it muffles plenty on its own. I have been running muffler-less for a while, and it's only a little louder than stock. I started it up for someone on new year's day. His comment:

"That's it?" I think he was expecting something more Harley-like.

If you are using the Y-pipe, not sure where 92Db is on the obnoxious meter. NJ hasn't cracked down on noise.. yet.

[sweatmark]

Need it LOUD? Then the cat will need to be replaced by a Y-pipe. My wife runs the cat & tip combo (without OE muffler) and her Roadster is a bit louder, but no discernable change in performance/mileage aside from the lost weight.

My Rockster has the titanium Ztechnik, which replaces both cat converter and muffler. Result is loud and obnoxious in its current condition... hoping a muffler repack will address the obnoxious part. Note that I purposefully separate "loud" from "obnoxious", as I have no problem with a loud exhaust if the tone is rich & full (e.g. the 102 dB Drummer exhaust on my Buell), and if the neighbors are all happy (I sometimes walk the Buell down the block when departing early).

We'd all love to know what tuning options truly produce power and/or efficiency gains. There's been a lot of scuttlebutt here on the R1150R board over the years regarding exhaust options, but little real evidence of bang-for-the-buck.

[Sunfire]

Yeah, I still have the cat. converter. I don't want it to be LOUD, just better sounding. I want to buy an exhaust not for the power gains, just for the cool sound of the boxer engine.

Mark, I had the Drummer on my XB12R, and although the sound was beautiful, I sold it because it resonated inside my helmet. If the Drummer was 102dB, then 92dB should be 10 times quieter than my Drummer. Am I correct in my calculations?

I've looked at all the other options available, but none make use of the OEM stock heat shield.

Decisions, decisions...

[boxermania]

ccRider91351

Akrapovic makes good systems, however, if you are still running your cat converter your claims of added HP are not more that a perception created by the slighter louder exhaust note by the muffler as the majority of the restriction on the exhaust system lies in the cat. It has been proven that cat and mufler replacement in the R29's will return 3 to 4 hp max.

TBR (Two Brothers Racing) used to sell the Y pipe (to replace the converter) for a little more than $100. I'm sure you can pick one up at eBay or BMWBoneyard.

Good luck

[jfslater98]

... make use of the OEM stock heat shield.

You're talking about the little shield near the left footpeg, correct? If so, you could just remove the muffler. The shield I am referring to has an adjustable clamp, so you can remove the muffler, and re-clamp the shield around the pipe that sticks out of the cat. You probably wouldn't want to do this on a rainy day, but you can hear how it will sound and even ride around a bit to see if the new sound bothers you.

If you like it, you could start looking in auto parts or muffler stores for exhaust tips that fit. While I don't have the heat shield on mine, this tip was $8 at RS strauss

http://picasaweb.google.com/lh/photo/WV ... directlink

[Green Hornet]

Here is a pic of a SS tip being used with the shield (turn backwards).

http://i467.photobucket.com/albums/rr40 ... CF0951.jpg


Micky

[sweatmark]

Paul,

Have you removed the OE muffler to hear the cat-only option? Easy to do, exhaust note deepens, and the weight reduction is noticeable. Recommend you try it before spending money on aftermarket solutions.

I'm looking into muffler options that will adapt to my Ztechnik y-pipe, if a cheap can is out there. We had a thread going last year about using a SuperTrapp/Kerker for old school effect.

The best boxer motor exhaust I've heard is on my buddy's 1973 slash5: deep, rich tone, and just loud enough.

[zax1150]

http://www.exoticsportbike.com/r1150r_rockster.htm

if you want a nice increase you could try the hot cam system I find it to be very crisp when I grab a hand full of throttle

And loud enough when you blip the throttle in london traffic

[Old Crockster]

Have you considered the Bos perfomance system?

[marc.wolters]

Hi,

I also have the BOS exhaust system installed. It's the muffler and the Y-pipe, and they ship it with a special EPROM chip, which need to replace the standard one. It's programmed to deal with the different airflow out of the new exhaust, without catalyst.
After that the sound is GREAT (sounds like a Spitfire airplane if I give my Rockster full power), the power has increased with 7 BHP. And if it's not loud enough, you can always take out the DB-killer in the muffler (I did that, but I like the neighbourhood I live in, so I put it back in again )

Check out this picture:
http://picasaweb.google.com/weekend.mot ... 6542585618

Also some info on the BOS-site:
http://www.bos-exhausts.com/bmw-eng-pond/index-bmw.html

Enjoy your search

[Sunfire]

Thanks everyone for all your info. I'll post an update when I decide what I'm doing with the exhaust.

Paul

PS What's up with this weather in the East? I haven't taken my bike out for about 4 weeks now...

[boxermania]

There isn't much to be gained by external mods to the R29 oil cooled engines. Based on my own experience, with the dyno and what other users have posted the following is pretty much what can be had:

Aftermarket muffler and cat eliminator, iregardless of brand - ~ 4 HP
Techlusion R259 at factory recomended settings - 3 HP
The two above with a 3 degree ignition advance (max avilable) - ~ .5 HP, for a total of 7.5 HP
Air filter replacement - no gain observed
Air horn enlargement - no gain observed
All of the above with Autolites 3923 gapped at .030" and running 89 octane gas (no blend)

The gain is about 9 %, not too bad, considering how it wakes up the engine both on the midrange grunt and crisp acceleration into the happy zone.

[spoon]

There is a thread in advrider.com on exaust changes for the GS. This would apply to any of the 1150 oil heads. My question is by removing the cat will the engine temp be lower. I would think that the cat is a restriction causing higher operating temps - along with a leaner mixture. So remove the cat, richer fuel map = cooler running engine more power at the expense of fuel mileage. Thoughts with numbers?

[Trompie]

Pickedup a 2nd hand Two Bros plus Y-pipe like new for R1500-oo ($140), what a sound . We had a dyno day yesterday with our club. I don't like to put my bike on a dyno but seeing that there were a few BM's I gave in. The figures in brackets BMW specs: 93.5 hp (83., 116N (98) top speed 207km/h. I'm happy . I use to have a stubbie plus cat, but boy these pipes sounds

[marc.wolters]

And now..... curious as we are: pictures please

[Beaze]

Thanks everyone for all your info. I'll post an update when I decide what I'm doing with the exhaust.

Paul

PS What's up with this weather in the East? I haven't taken my bike out for about 4 weeks now...

Yeah it SUX is what's up....can't wait for spring to fully arrive!

[shake1150]

hi there,

If you are looking for an exhaust pipe that utilizes the stock heat shield, try looking at a Zach exhaust.

http://www.boxer-design.de/en/detail.asp?ID=6&pID=141

in the picture on the website, they dont have the heat shield installed. but I have the heat shield installed on mine, and it looks like a stock setup (see pic below). sounds much better than stock... deeper tone. I also have a Rhinewest performance chip installed.