Wondering if I'm going to run into trouble @ altitude (4500+ ft) on a 91 octane mail order tune from Will @ Overkill. The TCM tune should be just fine, the timing advance is what I'm concerned about, I've heard that people run into problems when using tunes made for sea level vs altitude. I've also heard that more timing can be pulled at altitude to help compensate for the oxygen density losses (indirectly).
I'm planning on feeling it out and seeing how the new ECM, TCM does, possibly get Will to tweak. Shipping and reshipping to get this right isn't the most time effective process. I could probably tweak the tune on a dyno ($$$) looking at another 300+ unless someone knows a cheap dyno tune in Utah.
If altittude is an issue how would it manifest itself?