ORIGINAL: StantheMan

I live onthe outskirts of Denver, not quite as bad a Leadville which I believe is above 10,000 feet in altitude compared to my 6,000 ft. in altitude. Also, not only does Colorado have less air, but we have to contend with less octane in ourfuel. Regular gas here is 85 octane, mid grade 87octane, and premium is only 91 octane. When I purchased my tuner from Brenspeed, they specifically set the tune for the lower octance and higher altitude, I am sure that my Stang would run much better a lower altitudes, but having a tune specifically set for high altitudes and our lower octane fuel helps quite a bit.