How much do mods affect the resale value of a car, if its a tuner car thats directed towards people that like that stuff. i have a cold air intake, a racing header and a catback exhaust for my 2003 specV that I havent out on yet. Im gonna be trading the car in around january or so and I really want to put these parts on my car and drive it around until then. Is it worth it or should I just sale all the parts on a forum before they are used?