If you are going over the rails, I would have it lined first. The place we use here, will not line over fresh paint. They have to strip the paint off the rails, and the take a chance of messing up the new paint you just put on. Besides if your going back with black, when they cover it up the plastic is going to leave fine scratches in the new paint. Believe me I know. I have don't paint and body since 95'.