I am a new owner of a a Z06(1 week ) and the usual first performace upgrade on my previous cars was to install a after market air filter system. I have been looking at all the ads of course with claims of 10 to 40 hp increase with the installation of their product. I have used K&N in the past but there seems to be a much wider choice for Vettes. Does anyone have any real person data on what has worked for them? Or can you provide a URL to a comparison evaluation of these products? Most of the ads make me think they are selling snake oil. The 40hp claim seems especially suspect, GM could not have put THAT restrictive a stock air filter system on the LS6 engine.