If you want 400whp, here:
ID1000 Injectors
Walbro 255lph pump
GTX3572R rotated manifold turbo
ETS FMIC
EWG
Killer-B ELH + rotated EWG UP (does this exist yet?)
E85 flex-fuel kit
Tuning solution (obviously)
TGV deletes
Parallel fuel rail mod
IAG fuel damper kit
IAG AOS
Snow performance Water/Meth injection (you'll need all the det-resistance you can get)
Catless DP
Speed-density conversion
Killer-B Oil pan, baffles, and pickup (you'll need the extra oil capacity for cooler oil temps)
That should make 400whp on most dynos. The motor may last 100,000 miles or 1,000 miles. At these BMEPs, the motor could go at any minute.
Sure, you could build the motor for another $8,000-10,000 and it MIGHT last another 50k miles, but built motors rarely last as long as stock OEM motors.
At the end of the day, you might have an Impreza that cost you $65,000 and resells for $25,000. Or you could have a $40,000 Camaro SS (with 400+whp mind you) that resells for $38,000.