thermal said it best - "Dont waste your time and money on bolt-on performance systems like header, intake, exhaust." The best bang for the buck by far is nitrous - for less than $500 you can add 50hp to the car. Lower heat range plugs and a good kit that adjusts fuel regular pressure dynamically (look at Zex kits) is a safe, easy and cheap way to add some decent power. Just save up some money for items that will wear more quickly due to the added power (mainly the clutch.)