[bobcowan]

You lose about 2-3% per thousand feet. Give or take. I live at 6,400', and my car makes pretty good power. I was at hastings recently; 2200'. Wow! What a differance. That extra 10-12% is really noticable. Since I have EFI, I just drove it off the trailer and onto the track. No tuning needed.

EFI will maintain drivability by adjusting the fuel curves for altitude. But it won't give your hp back. The only thing that can do that is FI.