tbh i'd only advise getting a back box, as a full system will not offer a great deal more power to your car, it may feel like it makes it loads quicker, but its more physcological than anything! imo you should just get a back box and save your money, that way you get a lovely sound, then if you want it louder, get yourself an open induction kit £40-£99 (depending on which one you get) and that will make it sound aggressive.