A stock 04 gets 305hp to the wheels. You can't just throw things on a car and expect the numbers they say. You need to upgrade your entire exhaust system and tune it. Everything from ignition wires to your tips. If you get headers and still have stock exhaust, you will lose power. Even more so with a cold air intake. You will get a bunch of air, but not enough gas to your injectors. This results in a power decrease. Then again, some companies make crappy parts that don't do what they say they will do.