[Graystone]

Most of the the other Exhaust are claiming anywhere from 10 to 13hp. But I cannot find any documentation on even a claim of hp for the Bmw sport exhaust. Oh and possibly weight savings .Does anyone have an answer.
Like the idea of a Bmw part but the fact that all say its more layed back makes me think that the gains are very minimal...2horseys or something ridiculous like that. Mine as well leave the original, right! Tks.

[kirby135i]

bmw perf exhaust claims 5hp on bmwusa site.

[Graystone]

I was thrown when i went to this site. It showed a 328 and upon further study found the 335i . 335i 5hp at 6000rpm, 328 5hp at 6600rpms.....
Pathetic........................ sorry for not seeing it but all the same now guys can search here and find it.

[ShortCkT101]

Not enough for you to even notice

[chumley]

I'm guessing either the factory exhaust is better engineered than it looks, or the exhaust (past the downpipes) is not all that important on these cars. As you said, the boldest claims by some of the exhausts out there claim best case 10-15hp and while I'm sure that they would like to believe that it comes from superior engineering, most of that gain is coming from deleting the secondary cats and spec'ing a muffler than is less restrictive (louder).

As pretty as these stainless mandrel bent exhausts look, if you left the factory cats in place and ran "quiet" mufflers, the gain would be less than the margin of error between the dyno runs you'd need to test for any gains. 3-5hp is not significant IMO.

That said, I gotta say that some of them, like the Bastuck axle-back for instance, make the price almost seem worth it for the sound alone. For some people the audible feedback is just as important and performance gains.

[scott@bmwhn]

rule of thumb for me is "buy it for the sound and build quality, not the performance". gains are negligable unless you start playing with the cats

[SV Concepts III]

Not only that but you will want a software upgrade to take advantage of the improved flow.