The only trick to assembly beforehand is there is still a fair amount of bend to the roof/rail. There is a little leeway if you are off on the center of the hole, but not much. Hopefuly you have someone to help you hold in place (flex it down against the roof) while you mark the hole positions to drill. I wish I had thought of taking the camera with me for it, I'll be very interested in seeing how the headliner drops
