Originally Posted by BGM
the exhaust system is very restrictive on the m3, it will make a difference
I guess the key question for me is how much more restrictive is it compared with the standard 335i muffler as I had a look at the piping for both and the size is nearly identical which in my mind puts them on close to a even playing field.
After finally finding a cross section of the M3 muffler it seems for every two outlets there is two sections in the muffler (making two pairs of identical sections) so there are two Hemelortz (I dont think I spelt that right) sections and two sections where there is sound dampening fibre and the piping is perforated. But I guess the key point is that the piping does not reduce in size through the muffler.
I used to think that this would be a bad thing as it quietens the exhaust bark quite a lot but since this is my daily and I dont really want any unwarrented attention from the boys in blue, my conclusion is that provided I meet my performance goals, I will leave the muffler as is.
I'll be posting some of the other things that will be going onto the car soon!