The stock M3 muffler sounds great to me, but the youtube video's of the "Meisterschaft GT" is intriguing. Who/where does this muffler work reliably, if the 'need' arose? Does it affect performance at all? I know nothing of this topic.....
I know of a friend who has this exhaust system on his M6 Cab, and it does sound great. It is essentially a "knock-off" of an Eisenmann Exhaust system. I have heard both systems on M6's side by side, and personally I love the Eisenmann better, but if you use your M3 as a daily driver I would try an exhaust by AC Schnitzer http://www.ac-schnitzer.de/en/, or wait for the Dinan Exhaust. I've attached links to the 2 M6's below. The Eisenmann is LOUD. The car can be heard for about 2 miles, and it sounds like an off-shore racing boat!! As for the performance aspect, it is negligible. You will gain 6-14HP, but at there really isn't a noticeable difference (if you can tell that you are getting 10hp more then call BMW b/c you can race for them). You will notice a more immediate throttle response, but again, actual real performance gains are nominal. M6 with Meisterschaft GThttp://www.youtube.com/watch?v=cA7-ECkiJ14 M6 with Eisenmann http://www.youtube.com/watch?v=rxd2ln81mbM
muffler Loud probably not practical in the daily commute---interestingly, with the current muffler, M-dynamic mode active and the power button pushed I have already (inadvertantly) scared drivers when I passed. Schnitzer sounds good---thanks for the links, I'll check this out.
There's also a Eisenmann Sport exhaust that's not as loud as the race version http://www.youtube.com/watch?v=memZ-SQmp-o
