BMW Performance Exhaust question (135i)

[Si-M240i]

I am having one fitted in 2 weeks and was wondering what sort of BHP / Torque gains to expect? I also run an ITG replacement ari filter which has made the car feel a bit brisker higher up the rev band in the first 3 gears.

As I am in th UK I run Shell VPower petrol which is 99 RON.

[TT1351]

I think BMW claims about 5 HP increase for the exhaust, according to their accessory catalog. Torque I haven't seen any figures on.

Fran

[Si-M240i]

Originally Posted by TT1351

I think BMW claims about 5 HP increase for the exhaust, according to their accessory catalog. Torque I haven't seen any figures on.

Fran

Thanks for the information. I would like to think with the air filter as well I may see about 10 BHP.

Si

[Chicago1]

My Service Advisor actually deterred me from BMW's Perf. Exhaust, stating that it won't see much HP gain, sounds pretty modest ("..better than stock, but still pretty mild.."), and that there's much better aftermarket setups already out there, with more coming. He also mentioned that something might be on its way from Dinan. I'm personally going with cp-e... ordering tomorrow

Sounds delicious!

Nick-

[TT1351]

Let me say this about the exhaust, I have had Borla, B&B, Supersprint, UUC, Eisenmann and Ansa exhausts on my cars over the years. The Supersprint while excellent quality, but were very quiet apparently for European noise regulations. Borla were ok but was never impressed with the look, I still have one on my E30 JS M3, B&B loud and boomy, sill have one on my LTW kind of fits the cars character, Ansa on an old 325 xi, quiet and cheap, UUC (Corsa?) on another M3, looks good sounds good, Eisenmann on my recently sold E46 M3, looked awesome but boomy at legal speeds, quiet at 80.

Which brings me to my point, on my 135i, I ended up with the BMW performance exhaust for two reason, maybe three, 1, it was available, it was fairly reasonable, and it was warrantied and well made, albeit heavy. The sound is very mellow at low RPM, above three grand it howls, while not noticeable with windows up, with windows down between two buildings or a tunnel the song is incredible. As far a performance claims I was just quoting what BMW states, to me it doesn't feel any faster, but at the end of the day it is a great system and I don't regret installing it. I figured I would buy it to have something on the car and then get something else when it would become available, but I'm staying withg tthis one. Just my 2 cents.
Fran

[Red135]

I agree with TT1351. I have the exhaust and I really like it.

[Chicago1]

Oh, no doubt the BMW sounds good... I was *very* close to pulling the trigger on the BMW exhaust with Dan at United BMW, but my personal preference is the cp-e. IMO, it sounds more "exotic" to me..

[TazioNYC]

I feel like the exhaust made my car feel a little zippier, a little more oomph. So I would believe the 5 additional hp claim.

[mjovic]

Originally Posted by TazioNYC

I feel like the exhaust made my car feel a little zippier, a little more oomph. So I would believe the 5 additional hp claim.

5hp gain for a catback is frankly rather laughable. I am considering this exhaust for two reasons, sound and warranty.

[jkp1187]

Originally Posted by mjovic

5hp gain for a catback is frankly rather laughable. I am considering this exhaust for two reasons, sound and warranty.

Laughable? I think a 5 HP gain is more or less what I'd expect from an exhaust that leaves the factory cat and downpipe in place. Anything more than that is more likely to be mere marketing puffery.

[tjockey]

Originally Posted by Chicago1

My Service Advisor actually deterred me from BMW's Perf. Exhaust, stating that it won't see much HP gain, sounds pretty modest ("..better than stock, but still pretty mild.."), and that there's much better aftermarket setups already out there, with more coming. He also mentioned that something might be on its way from Dinan. I'm personally going with cp-e... ordering tomorrow

Sounds delicious!

Nick-

I've got the cp-e and it rocks.... I installed it by myself and it is amazing how heavy the OE exhaust is compared to the cp-e. That alone, not to mention the intoxicating sound it makes, is enough to justify the cp-e. If you have any other intake or exhaust mods or a tune, this is the only way to go...:thumbup:

[TunedM2C]

I personally love my Meisterschaft GT exhaust. On WOT it sounds exhilarating!

Here's my previous High Performance (HP) version:

[TazioNYC]

Originally Posted by mjovic

5hp gain for a catback is frankly rather laughable. I am considering this exhaust for two reasons, sound and warranty.

That's why I bought it as well. But I'm just telling you what I felt -- there has been some discussion about the dyno results of the 135 vs. 335 and how it's likely related to difference in the exhausts. That's why I think that ANYTHING you do to free up the 135 exhaust is going to let some more power out at the wheels. I'm sure something more aggressive would help even more. The cp-e would be the non-BMW perf one I would go for based on what I've read here and the clips I've heard.

[Chicago1]

Originally Posted by mjovic

5hp gain for a catback is frankly rather laughable. I am considering this exhaust for two reasons, sound and warranty.

Just a note regarding warranty, for those considering intake/exhaust mods:

I spoke at length with my Service Advisor the other day regarding an aftermarket exhaust. The deciding factor between BMW Performance Exhaust and the cp-e for me, was going to be warranty. My guy assured me that BMW would absolutely make NO fuss about a 3rd party cat-back exhaust, or intake, further stating that he's "been in the business for years, etc" and never seen BMW deny any kind of warranty service based on intake/exhaust mods.

That conversation helped me decide to skip the BMW branded stuff.

[Redbeemer]

I have a question: from what I have seen of the BMW perf. exhaust, it basically looks just like the stock exhaust minus the resonator, but with chrome tips instead of the smoked chrome. So I am wondering out loud if anyone has thought of simply have an exhaust shop cut out the stock resonator and weld in a section of pipe to connect the remaining exhaust pipe to the stock muffler? I am guessing that most of the increased sound of the perf. exhaust comes from just removing the resonator and that you might get around 5 hp extra from removing it. Any thought on this?

[Chicago1]

Originally Posted by Redbeemer

I have a question: from what I have seen of the BMW perf. exhaust, it basically looks just like the stock exhaust minus the resonator, but with chrome tips instead of the smoked chrome. So I am wondering out loud if anyone has thought of simply have an exhaust shop cut out the stock resonator and weld in a section of pipe to connect the remaining exhaust pipe to the stock muffler? I am guessing that most of the increased sound of the perf. exhaust comes from just removing the resonator and that you might get around 5 hp extra from removing it. Any thought on this?

+1 ... hmmm - I wonder? Good call.. Has anyone seen an internal view of the stock vs performance muffler?

[jkp1187]

Originally Posted by Redbeemer

I have a question: from what I have seen of the BMW perf. exhaust, it basically looks just like the stock exhaust minus the resonator, but with chrome tips instead of the smoked chrome. So I am wondering out loud if anyone has thought of simply have an exhaust shop cut out the stock resonator and weld in a section of pipe to connect the remaining exhaust pipe to the stock muffler? I am guessing that most of the increased sound of the perf. exhaust comes from just removing the resonator and that you might get around 5 hp extra from removing it. Any thought on this?

This is a very good point. Can someone who owns the performance exhaust measure the diameter and circumference of the pipe, and perhaps compare that to the standard exhaust? If they are the same, just removing the resonator might be a "poor man's" solution, no?

[holo777]

There is a thread out there where someone didn't like the perfomrance exhaust and put the stock muffler back on with the removed resonator. I think they said it was pretty much stock sounding afterwards. It sounds like there are fewer baffles in the performance muffler.

[ben14142001]

Originally Posted by Chicago1

Just a note regarding warranty, for those considering intake/exhaust mods:

I spoke at length with my Service Advisor the other day regarding an aftermarket exhaust. The deciding factor between BMW Performance Exhaust and the cp-e for me, was going to be warranty. My guy assured me that BMW would absolutely make NO fuss about a 3rd party cat-back exhaust, or intake, further stating that he's "been in the business for years, etc" and never seen BMW deny any kind of warranty service based on intake/exhaust mods.

That conversation helped me decide to skip the BMW branded stuff.

Only problem with this is that the cp-e, unless you choose the axle-back option, will not be a cat back, since it will replace the cat in the mid-pipe. I've found in my experience with dealers (although, this is my first time with BMW) that axle-back and actual cat-back systems are generally not frowned upon because there is very little that can go wrong. Once you start removing cats, which almost every aftermarket exhaust system for the 135 does, they start getting a little bit more void happy. Although I know removing one cat will not make a huge difference, I think it is generally frowned upon by dealers with warranty claims on their hands. JMHO.

-Ben

[Rye]

A cat-back itself won't produce large gains, compared to other mods. Need to replace the downpipes to see some really good numbers. Buy the cat-back for sound, not for performance.

[Bullitt]

BMW states a performance gain of 5 HP, but they also tend to be conservative with their numbers.

The following are pics from an ebay auction.
http://cgi.ebay.com/ebaymotors/BMW-1...QQcmdZViewItem

The first pic is of a dyno is with the stock exhaust. The second is of a dyno after installation of the performance exhaust. You be the judge!

We do need more dyno's with the performance exhaust to confirm this.

[jkp1187]

Originally Posted by Bullitt

BMW states a performance gain of 5 HP, but they also tend to be conservative with their numbers....

We do need more dyno's with the performance exhaust to confirm this.

Agreed. One dyno result is interesting, but doesn't mean much (esp. when provided by a dealership trying to sell the car.) Dyno numbers can be "tweaked" sometimes, too.