welcome to the forum, as for power, engine management is verrrrry important in making reliable power on your wrx. do some reading on here before you do anything to the car. our motors are very picky to mods without engine management. Check out Cobbtuning for their accessport. it's one of the easiest to use imo. also... your factory bypass valve is the best thing to stay with. Bov's sound cool, but arent that great for your motor. the bypass valve recirculates that air it purges instead of venting to atmosphere like a bov. you can remove the little silencer thing on your inake tubing (in the fenderwell) to get a little more sound. have fun with the wrx!!!!!