Alright, here's the software you can use to "dyno" your car. But unfortunately it's not free. I read about it in this thread:
http://www.wrxfanatics.com/index.php...=dyno+software
http://www.dynamic-dyno.com/
I've heard good things about the software and the guy who made it. Apparently he's very helpful if you have any issues setting it up. His name's Tony and he's an enthusiest from ClubWRX.
But if you have Ed remote tune your car, it'll be tuned to optimize performance at this elevation and you'll get pretty graphs.