Update: It's been a while since I posted and no comparison yet. I've been doing some cosmetic mods: black & white BMW roundels (wheels, hood, trunk, steering wheel), Shadowline Grill, Front Splitters, and other odds/ends. What I've decided on after some debate is to get the Dinan exhaust. They're black chrome tips, and sounds a little more aggressive. The regular chrome tips on the BMW Performance Exhaust really turned me away. Just one less thing to have to mod on a mod.