gruppe-s has GOT to be the best power - money results... i mean $399 for a freaking set of headers shipped to you is awsome. Cant get better then that, that and it keeps that boxer rumble... dont ever get rid of the rumble... the sound is far better than an extra 2-3 hp
I personally would opt for the deal that ChargedPerformance.com has on the GT Spec Gen.II headers. For $679 you get:
-GT Spec Gen.II headers(better pipe design than Gruppe-S and they have a more sturdy 3-bolt collector design..better in reducing the risk for leakage)
-GT Spec Gen.II up pipe
-both headers and up pipe ALREADY Jet Hot Coated with 2,450 degree thermal coating
Thanks to Charged Performance for the picture.
The Gruppe-S header w/up pipe costs $500, but it would be wise to get the header ceramic coated for better heat retention = more efficient exhaust flow. In the end, it will probably cost just about the same as the Charged Performance deal. However, you get an improved pipe design and no "down time" when shipping headers out for thermal coating when you go with the Charged Performance deal.
***BTW, the Gruppe-S headers are based off the GT Spec Gen.I pipe design.
gruppe-s.com . although Im going to go with the GTspec as well, their design seems a lot better and is a great deal at $500 for header and upipe and all gaskets... find it at www.godspeedinc.com - gtspec. so please excuse my first post