^I agree. I will say get a tune on the car to make it a little happier (yes more power) and find a stock recirc valve. Then maybe focus a little on suspension and just driving the car. Once you feel you're ready for more jam then 300whp is certainly easily obtainable. I personally recommend going with a 18G or maybe a 20G either with an 8cm^2 exhaust housing. My 02 WRX made 310whp and 285wtq (3700rpm) on a dynojet, 93oct and about 20psi boost with a Blouch 18g 8cm^2.
I miss that car. Sold it to a friend and he blew the tranny in 3 months. It lasted me 130k miles (10k @310whp, the rest at 230ish) So that brings me to my next point. The 5 speed will last as long as you shift well and dont launch the crap out of it. But once you get to these power levels you really are just on borrowed time. Save for a 6speed swap.