My 2002 wrx has a Powertec sl1 cold air induction system, was just wondering if I changed it for a k&n57i or hks mushroom would I see any benefit, don't want to spend the money not to see any gains, I know some will suggest going back to original airbox but car has been remapped for cold air induction so want to stick to this system, car also has decat exhaust and dump valve, thanks, Robin