It's for an 02 GT. I have a ported intake and throttle body, Cold air intake, billet throttle body spacer, and UPR X pipe. is it possible that i am running under 260 HP?

 

Dyno time in my area runs $50 for three pulls. If I were figuring the total cost of a custom tune (including the cost of buying a flash tuner) I would estimate $400-$500. My car was running very lean after the mods I installed and needed it. It is possible that you are still running under 260 HP, and my guess is no more than 250 HP.