Quick exhaust question

[six-n-twins]

It looks like BMW is ready to revoke all warranties if you even think about modding your 135. Does a simple cat back exhaust effect your warranty? Ive heard stories about mitsu and subie cancelling them for exhausts. Ive also heard that it is not legal due to the fact that a cat back couldnt cause increased wear and tear, failure etc. Which is true?

I can see that they could argue that the turbos can spool faster with a catless dp, more power and faster spool, but a cat back usually adds nominal hp and is more for sound.

[Red135]

I know that there are plenty of people on this forum who can answer this question better than I can, but the short answer is no, BMW wouldn't be able to prove that a cat-back exhaust was a direct cause to any issue that would be a problem.

[TunedM2C]

I've always had some form of exhaust on my past BMW's and they (dealer) never red flagged me for it.

[jeremyc74]

It's perfectly reasonable to think that a cat back exhaust could cause a turbo engine to operate outside it's operating range. I don't personally think a cat-back is going to cause you to blow an engine, but if you have issues with a turbo failure or somthing related, you're certainly opening the door for them them to question it.

[morscode]

Agreed. I've had an exhaust on my Z4 and an issue has never came up in the past three years, in fact they usually rev her up a bit to enjoy the noise.
But the Z4 is no turbo motor, so I'd be on the fence.

[ScottyGams]

mag moss act... no blanket void of warranties

something has to go wrong, and then BMW has to prove it was your modification that caused the failure. Very rare an exhaust can be blamed

[F0Bman]

It should not.