Great insightful review. Exactly the level of detail to help others make decisions ... except ... I was soooo wanting to not get a Performance Exhaust, but your review and many others all point to it being the best option.
My friend has one on his E93 330 and we both find it really quiet on start up and cruising/general driving. Granted, under hard acceleration and high revs it sounds great, but I don't really want to have to be blasting it all the time in order to hear the exhaust (just turned 40 so i must be maturing). I was going to go the Eisenmann route because of this, but all your reviews of the PE are excellent and you can't all be mistaken!
I wonder has my friend been ripped off and he hasn't actually had a PE installed after all!!