I recently bought a 1999 2.5rs. It has (forgive me if I get some specs wrong, I am somewhat new to Subaru engines) a 2.5 litre engine. Would boosting that engine not yield more power than swaping for a 2.0 litre WRX engine? I am leaning towards boosting because I am not really setup to remove and engine and replace it! Plus Ive never done that before!