i am new to wrxs and i am getting one this week. looking to get basic mods but i would like to get 300hp to the fly. i am looking into getting up/down pipe, cold air, and maybe a cat back. what are other mods that would be effective? oh and how much more hp does the hks downpipe add then a regular style downpipe that keeps one of the cats? i need to keep the car street legal so i dont want to remove all the cats but if it costs alot of power it may just have to come off. if its possible could i have a list of mods and how much hp each one adds... thanks any help is appreciated.