Why is my car slow? =(

[TGPilot]

I was 1ce told by a STI guy that altitude really doesnt matter as much on a boosted car as it does N/A because its still getting plenty of air.

It most certainly does...higher altitude (say above 3800ft) you are not only in less dense air, but the O2 levels fall off. Less O2...less power no matter if it is N/A, Turbocharged, or Supercharged. A SC or Turbo car will do better than a N/A car at higher altitiudes...but the power does drop off... 8)