[un4gvn!]

I used the 2 inch industrial strength velcro from Lowes. It's pretty sticky. You want to wipe both surfaces of the ceiling and headliner down with denatured alcohol. When you unravel the velcro, both the loop and pile will be stuck together. Leave them both together. Peel away the backing from one side. Press the velcro in an X pattern on either the ceiling or headliner. For extra strength, I cut 6 inch strips to attach to the four outer edges of the triangles you just made. Try to stay around 3 inch's in from the outer edge. Once you have the velcro tape attached to the surface, peel away the backing from the velcro. Leave both the loop and pile stuck to each other. Position the headliner where you want it. Once you have it squared up, press it to the ceiling making sure you're square. It's a real ***** trying to peel the headliner off to square it up. Take your time. Mine has been up for over 5 years now. No sags, no warping, and no signs of it coming off. I used the velcro because if I want to take down the headliner, there will be no mess from the glue remaining on the ceiling. I think the magnet will make the headliner hang a little low. The velcro makes it pressed up tight against the ceiling as you can see in the picture. The headliner is pretty thick, that's the reason I didn't use sound deadner.