It's your car, modify it as much or as little as you want... the difference in resale value will only be a few K. If your really concerned with resale value then the answer is simple, dont drive it......ever..... That will ensure you will NEVER get any enjoyment out of it but at least you will get a few grand back when you sell it. The odds of a car ever appreciating above MSRP in a lifetime are rediculously low. It's not an investment (a wise one anyway) so stop worrying about how much you can sell it for and just have fun.