As an FYI, the '06 WRX is actually under-rated at 230hp.
This is a stock vs stage 1 dyno graph on Cobb Tuning's awd Mustang Dyno for a 2.0L '02-'05 WRX (rated at 227hp):
This next dyno shows stock vs stage 1 for a 2006 2.5L WRX on the same dyno (rated at 230hp):
Are you going to keep an auto trans in your SVX or have you also done a 5/6MT swap? If you stay with an auto, I'd highly suggest switching to a Legacy 4.44 4EAT. On a 3,500lb car, this engine is going to feel like a dog when off boost, and shorter gearing will be beneficial.