How coincidental, on my way to work today, I was stopped at a red light next to a M4 who was in the left turn lane. I made eye contact with him and gave him a thumbs up. As the light turned green, he revved his engine twice, on the 2nd rev he went on his way (obvious 6mt trans).
While I enjoy a nice exhaust, it's definitely not an end all decision for me in buying a car. IMO, my M2 with Fabspeed sounded better than that M4, but I didn't think it sounded bad. If sound was the #1 criteria for me, I would have kept my 370z with aftermarket exhaust. The M2 is defintely the better overall car vs the Z and I'm very happy to be a M2 owner, however there are some other 6 cylinder cars that sound very nice. Not my car below, but for those of you who have never heard a VQ 37 with an exhaust, here's a good example.