I'm sure everyone here is annoyed when driving down the highway at high speeds and not being able to speak with your passengers. So I started looking around for sound deadening media and came across this stuff from Thermotech (
http://www.thermotech.com). I went ahead and purchased 3 sheets of the 36 x 60 inch adhesive backed sheets (pn: 14620). I got the stuff knowing it was going to be a pain to gut the interior of the cabin... and it was. I went ahead and washed out the floor pan of the cabin with a damp clothe and mild neutral soap just to de-grease the surface to get better adhesion of the acoustical sheets. I then proceeded to layout my acoustic sheets and cut them to size, I tried to keep the sheets as whole as possible to avoid having many small tiles for the floor pan. I got away with making 3 large floor tiles and they 4 more filler tiles for around the transmission hump that is in the cabin.
To get the sheets to bond to the floor pan well I used 2 pounds of rice in a 2 pillow cases and proceeded to pound the crap out of the acoustic sheet to get it to stick to all the contours of the floor pan.
Looking back I dont think I would have gone with the adhesive backed acoustical sheets, I should have just gone with the sheets you throw down and dont stick to the surface or maybe I should have just peeled away at the corners of the sheet.