There's no bow in the center. There's only two in the back. I believe the original vinyl had a flap that glued to the center of the frame that kept it from sagging. I put a repro headliner in and it didn't have that flap. I just had to stretch the vinyl as much as possible and glue it on the end of the frame. A little heat will help too. I don't believe that plastic piece is being reproduced. You don't really need it but it does cover any mistakes when you cut the corners. That's one job I certainly wouldn't do again. If you send me an email I can send you a couple of pictures of what mine looked like when it was done.