I saved this DIY from the forum but have not tried it yet:
DIE Floor Tunnel Shield
1)Remove tunnel plate and write top on the top side of the plate.
2) Place tunnel plate over center of sheet of DEI heat shielding (adhesive backing facing up).
3) Trace outline of tunnel plate and "most" of the bolt holes along the perimeter.
4) Look at DEI material and make a free-hand line just inside all the bolt holes about 1/2-3/4"
5) Take a knife and carefully cut the adhesive backing protector along the free-hand lines you created and remove adhesive backing ONLY from the middle (see photos at bottom).
6) Place tunnel plate with "TOP" facing up, carefully over exposed adhesive backing using original tracing lines. Once lined up press onto the DEI material and press down along the entire tunnel plate.
7) Flip over and fold "wings" inward to expose your bolt holes. Trim wings down as desired.
8) Re-install tunnel plate bolts.
9) Press wings against tunnel sides to keep heat away from both the top and sides of the tunnel. You're done!!!
Here is a gallery of photos:
I've done this twice and I didn't secure them in any other fashion. Mine has held for 10k miles with no issues. The material is rigid so it holds it's form once you get it pressed against the sides of the tunnel. A rubber mallet can be helpful but watch what's behind the material. I've seen some people put a couple rivets in on the ends of the tunnel plate. Although the one I did in the photos we took to a Kansas City performance shop to install. The idiot at the shop removed the backing even though you can clearly see we wrote on both sides to not remove it. He said he thought it looked better No telling how we will get that tunnel plate out.
I used the DEI 010412 48"x36" it runs about $52 at Summit Racing.