I bought my 06 GXP a lil more then a year ago. I still have the handheld Diablo Sport tuner if you wanna buy it. If you want info I have gathered a bit from different sites over the past year. First thing is first, the stuff in my sig + an HP tune got me to 340 hp. So ya figure we start at 303 hp and with 100 bucks for the fenderwell intake and 500 for a dyno + tune got me to 340. Hit me up if you need help with stuff, I'm very enthusiastic about my GXP and know a bit about them in my opinion.