I agree with Z7What, actual Road/Track testing is the very best, but I don't have the time/resources of a Race Team so a few DYNO sessions are the best I can do. Haha. I do plan on road testing and tweaking the tune a bit though.
Larsen- Non of the guys doing the computer tunes can fully take the altitude into account. The computers in our trucks are programmed to maintain a certain Air-Fuel-Ratio. Since this is highly dependent on how much OXYGEN the engine is getting NOT how much air, it would be almost impossible to take into account the lower Oxygen percentage of our air with one of these computer tunes.
Once you start adding CAI's and exhausts, the amount of Air and Also oxygen can start to change outside the boundries of the Stock PCMs limits causing codes to trip.
From what I understand you have to essentially "Trick" the MAF sensor at altitude so it thinks its getting less air (less oxygen) than it actually is to account for the lower Oxygen percentage. Ill let you guys know my results!