My 2002 E46 coupe has the exhaust rattle, the "clunk" and a pronounced lag between off-throttle and on-throttle. However, my 97 M3 also had the clunk all of its long life and never seemed to cause any real problems other than annoyance. I'm due for the 1200 mile service, so I'll find out if the dealer will fix or even acknowledge the problems. I hate the usual explanation, "That's just the way M3's are." Or, "We didn't notice the problem when we drove the car."