His screen name on here is Basco, the one that replied here also. Certain cars that come with that amount of power are one thing, they are designed and engineered for that. These cars on the other hand arent. If or when you would reach that number/goal with these cars it requires alot more maintainance than normal. A goal of 400-450 is a little more realistic, but still requires a built engine with many supporting mods. I dont like sending people away from this site, as its alot more user friendly, and has just as much knowledge as any other site I have visited. But check out NASIOC.com as its a larger forum. You can join there and check out other peoples profiles and threads that have gone down a similar path as you are contemplating going down.
"2007 WRX- PPG'd, 20G- Tim Bailey tuned
Stage 2 2005 WRX