Originally Posted by saferisk
The most intresting thing I learnt though is that the M3 muffler does just exactly that but more so that even the stock 335i muffler! I only rev'd it a few time standing still but I think either it hasn't changed much or has become quieter, which I dont really mind so long as it doesn't impact the performance. I've requested that the workshop do a dyno with and without the M3 Muffler to see how detrimental it is to performance!
the exhaust system is very restrictive on the m3, it will make a difference