Matt R had the Invidia on his car and so did Sperry, you can as Sperry but he had an Invidia TBE for sale a while back. The Invidia is nice, I'm just not a huge fan of the angled look and the resonator hangs down a little too much for my tastes. I really like the Cobb but it is quite expensive and now they only sell it with a cat in the DP. There are tons of choices out there and if you are looking for a good vendor Rallysportdirect is by far my favorite, great service and super fast shipping.
http://www.rallysportdirect.com/