Go with a cold air intake, it's not that expensive but it doesn't increase your horsepower that much. Only about 8 or 10. But it's around 120 dollars. Or a racing preformance chip, cost a few, but really helps. Or maybe get some ECU upgrades, they can raise your top speed and acceleration. Or just spend alot of money and get a turbo.But don't spend it on useless mods, or alot of mods for that mater ecause it can lessen your engine's life.