Originally Posted by marcel b
HP Autowerks wrote that they took the midpipe of the 135. Maybe a difference between N54/N55 version of the 135
Sorry, maybe I didnt clarify. I had an aftermarket exhaust on the 135. The midpipe was replaced and I am going to test that piece with the stock M axelback before I start looking into a complete exhaust system.
The rear section of the M seems to have minimal restriction, the mids seem to be identical to the 1 series so I expect to see gains in power and sound. My 135 was borderline too loud and I anticipate the M with my mids in place to be similar if not identical.
My 135 is N54 BTW