Read this thread. Then make your own.
http://www.grandprixforums.net/threa...en-Cone-Intake

K & N's numbers where in comparison to the OEM air box. My car (2004 GTP Comp-G) has the K & N setup, but it was on the car when I bought it so I have no way to vouch for any gains. I suppose it all comes down to how restrictive the OEM air intake is in comparison and how much difference in delivered air temp to the supercharger there is. So you think K & N is faking their numbers?