I have a pretty serious gas mileage problem. I have an '05 GT with the usual light bolt-ons. I tested my gas mileage and it's somewhere between 10-15 mpg depending on how much highway driving I do. The air filter is fine, the car has only 9000 miles on it and drives perfectly. I am a college student and can't afford to keep filling this thing up every 200 miles or less! Any help would be greatly appreciated.