I cut into the headliner in the area where the roof will be cut out. I had to remove 2 wire supports and some of the glued on insulation. I should have worn a dust mask, the fibrous insulation is a bit dusty. Be sure to leave a good amount of uncut headliner at the perimeter so you have lots to play with when finishing the cut edges of the hole. Looks like I am going to make that hole tomorrow.