gxp05

This is not the site to ask about gxps lol. Visit ls1tech.com for much better advice. I have the diablo tuner and it made a very big difference, not sure about the numbers though. The guy that said something about hp tuning is somewhat of an asshat. The hp tune is better because of the fine tuning capability. But apparently you can call lew at diablo and tell him your mods and he can send you a custom tune (not sure how much). Hope this helps.