I will make some assumptions that you applied SAE correction to your dyno graph using the dyno software, and that's where you are seeing a 90hp difference. If that is the case, that is wrong. Dyno software SAE correction does not take forced induction into account, and using it on boosted cars at high elevations creates false high numbers. Particularly with turbo chargers... Supercharger cars seem to get along with SAE OK since they will operate at a static ratio
I originally researched this years ago when a Denver TT 350 went on a road trip to the east and stopped in Chicago for a comparison pass on my same model dynojet 248. He made far less than this corrected numbers in Denver.
And since I don't personally have any comparison graphs to show you, I googled it and found this right away:
Altitude Dyno Comparison - evolutionm.net
If you continue to search, you can find endless examples of this. There are far too many complexities and variables to attempt and apply any static % number to correct for altitude on a boosted car. You can give it something, but let it be known that giving it SAE is wrong. And half the guys give it SAE then also add another 17% for themselves. Lol and god forbid its not on a dynojet, there's another 15%!!! Lol