the stock intake is a cold air intake is good to 300 whp the same level as your stock cvt is able to hold before slipping. aftermarket Intake is just a noise maker. if you want to get one anyway make sure it has a box or your just sucking in hot air and doing worse than stock. Also, you will need a tune for an intake, so if you don't have an accesport and tuner lined up already you'll need that first. throwing an intake on the stock tune is a recipe for disaster. I suggest reading these forums along with NASIOC (WRX/Impreza forum) before trying to mod you car so you know what to expect, the cost and potential issues. Last thing you want to do is grenade your engine or trans because you just bought a bunch of stuff without doing your research.