I had to replace the headliner and original insulation due to age. These pre-cut insulation pieces can be made to fit properly but required them to be slid under the '67 Lemans' roof braces if you do not want to cut them. With some elbow grease and some wedges to increase the gap between the roof and braces, they fit in place. After a few weeks of driving, I found the car to feel warmer and more comfortable during the morning warmup. I can't wait to see if it help with the AC in the summer.