The sc is mechanically driven and will not spin faster at higher elevations to increase boost though a turbo can be adjusted to compensate. A machine feels the lack of O2/ft3 at high elev exactly like your body, as one 'breath' contains the same % of O2 as sealevel but there are much fewer total atoms/molecules. If sealevel has 1000molecules of 'air' per ft3 (obviously more just an example) at sealevel, 21% of O2 gives 210 parts of O2. At higher elevation, such as at 3000ft, a cubic foot of 'air' only has 900molecules total meaning the 21% of O2 at 3000ft is significantly less at 189 parts. Humans and engines must 'breathe' more and work harder to consume the same amount of O2 while above sealevel. No amount of ecu tuning on a sc ski will account for this loss, which is why the most stout na or sc V8 in the mountains runs like crap compared to its sealevel performance.