[bobcowan]

I have two tunes for my Haltech system - air cleaner and open stacks. That makes a huge differance. There are special maps for altitude and temperature, so you don't need to change the tune as the weather changes.

I live at 6,400' ASL. Last year we drove to Hastings, NB. We rolled the car off the trailer and onto the track. It ran perfect all week end. No need to even take the laptop out of the bag. The computer adjusted for air density all on it's own.