If you were to trade a car into a dealer to buy something new (Elantra Coupe), and it had a lot of mods done to it, would they give you more or less for it compared to if it was 100% stock?

 

Certainly not more. If everything is done exceptionally well, maybe as much as stock. If it's not 100% great you should expect to go down from stock value.

 

If your trading in sell your more expensive parts and go back to stock. or better yet sell your car first then use the money to put down payment on the new one. Dealers always try to rape you on trade ins so they can make more money when they sell your car again. my .02

 

Any mods will deter from the value.