Great write up and review. I love the videos, but I'm always thrown off by how mean and loud exhausts sounds when it is filmed. It never seems to be that loud in real life.
I also like how BMW is pretty honest/conservative about the exhaust performance gains. About 5hp above 6500 rpm. It tells me two things 1) BMW designed the stock exhaust pretty optimally, 2) BMW isn't trying to sell you snake oil performance. Just good sound and a little bit of power.
If it was from some other aftermarket companies I've experienced the claim would at least be 15bhp through the entire rpm range LOL
2011 328xi Touring: Alpine White, Oyster/Black dakota leather, 6MT, ZMP, ZPP, ZVP, ZCP, Harman Kardon sound, iDrive, roof rails.
2007 Corvette Z06: Le Mans Blue
(yep GM used it too), titanium leather, 2LZ package, Bose sound system