I went and got some of the stuff from Lowe's, it works great. I have enough left over to do a couple of vehicles. The stuff is 1/8" thick and made a huge difference. Thanks for the input.
I also used it today and it made quite a difference. I used 3 layers on my trunk lid and still have about half a roll left. It definitely helped the trunk lid from rattling and flexing, but i still have to do the rest of the trunk.