I too noticed a large difference with the CAI. I had the Gen II Stillens first, then did the exhaust system and cats. Noticeable power difference and especially better sound! However, when I changed the Gen II's to Gen III's, I noticed even more power gains on the butt dyno. Especially at higher RPM's. Overall I found the Gen III's a better performer on the butt dyno and would say they are definitley worth the upgrade!
As I do not track my vehicle, the only numbers that matter to me are the $$ going out the door!
