here: http://www.perth-wrx.com/vb/your-dri...005-sti-~.html

The guy who owned this car spent A LOT of money getting it to 400hp with all the forged internals. If you want 400hp on a subaru this might be a good place to start understanding what it takes, will also give you a realistic idea of hp for the mods you have. He also mentioned that it spooled around 5k rpm which may not be what you want.

IMO you would be better going with rosco's opinion of sitting it at 300hp~ you would get the best of both worlds with a quick spool and plenty of punch.