I have a JDM WRX which is different from MI WRX which is Euro spec. JDM WRX have a close ratio 5 speed gearbox and it is rated at 260 HP on crank.
But at 1.4 bar and with ECU tuning & a VF30 Turbo from STI 7, my car has crack more than 290 HP on wheels (GT 4 WD dyno).
But the joke is that in lieu of preserving my engine in Sepang, I am now running 1.0 bar boost. At 1.0 bar, my feeling is that I can hardly crack more than 220 on wheel HP.
High boost in Sepang means painful to the pockets when engine blows.
STI V8 has a semi close deck engine and it is more hardy than WRX engine.
So in final analysis, go for a STI 8 or newer.
My best recomendation for STI
Spec C, , year of manufacture 2004, you have a car having the mechanicals of a V9 but in a body of a V8. So good buy as you need not pay for a V9!
PCD for this is 114 as opose to 100.
So you have a great choice of rims, which is much cheaper than PCD 100.
James