If your selling your house and it has a swimming pool then it may add value to some people if they want a pool. If the buyer doesn't, it takes away from the value. Who knows, the person looking to buy your car in the future may want it because of the changes you made and be willing to pay a little more because of that. If it is not a super valuable car then do it the way you want it. You will be happier having the car your way and that is really what matters. Remember, these cars were built at a time when customizing them was what you did. You made them yours by making them unique. It was only after they became investments that it became taboo to personalize them.