The first thing you need to realize is that the dealership is going to low-ball you on a price for your trade in, aftermarket parts or not. If you've still got your stock parts laying around -or can get some cheap- it's a good idea to swap out what you can and sell your aftermarket stuff separately.

The thoroughness of the trade-in appraisal depends upon the dealership you take your car to. Hall Nissan on Jefferson went over my car with a fine-tooth comb bumper-to-bumper and everything in between. Victory Nissan looked at the outside, said "nice rims," and then drove it around the parking lot in first gear for about 3 1/2 minutes. The trade-in price they offered me was $4,000 over what Hall had quoted me earlier the same day.