I don't see you hitting that with the stock turbo. But, anything's possible.
1. The STi already has a catless uppipe, you don't need to buy one.
2. Get a full 3" turbo back, UTEC, and some good dyno time.
Tuning is key, so make sure that you dyno somewhere reputable. This will give you an idea of where to go from here. Also, ask the tuner what he would do to reach those hp goals that you have set for your car.
My car is well, it's like 10 lbs of shit in a 5 lb bag...
<------ Click to see what I'm workin' with. ;)