The 2010 Mustang GT with Track Pack already puts up similar performance numbers as the 335 in acceleration, braking, lateral g's, etc. Add another 85 hp to that and it won't even be close stock vs. stock. That being said, they are very different cars. Both are good-looking cars in their own right. Both will make good daily drivers. It's really just a matter of choosing whether you want American Muscle or German Engineering.
Well, that and the price.
'08 AW 135i, MT, Terra, Walnut Burl, Sport, Premium, Nav, iPod, Premium Hi-Fi, CA