Can I chime in ?..........2008 WRX 5 door here ,
Mods are , perrin cai , perrin intercooler , invidia 3" downpipe , spt exhaust , and perrin stage 2 93 octane map wit perrin inatke !!!!!
I started with a cobb stage 2 map 93 octane , that required 3" exhaust ( stock intercooler allowed) , it was a huge improvement , maybe 210hp / 250tq to the wheels , but I wanted more , but the plastic intercooler can take only so much . So I moved on a and put a intercooler on , and a perrin intake with a injen hydro sheild , as usual , loaded up perrins stage 2 map , 17.5 peak tapering off to 10psi at redline . It was a huge difference , much more aggressive than a cobb stage 2 . I'm gonna guess 220hp/270tq , but who knows , I need a base line dyno . I've been driving like grandma for a week now , with city driveing Im getting 21.5 mpg , and that's when I'm not boosting so you have an idea , I'm most likely going to upgrade the turbine , its pissing me off , I wanna put down 280+hp@15psi at the most ..........enjoy the intake on 3 go !