What you do also depends on what your goal is. The jute that Horvath used has moderate sound deadening capability and no heat blocking to speak of. He did indicate he intended on a heat reflective material in phase 2, but I'd say he got it backward.

Another relatively low cost material I've used is available in most home supply places. It's essentially a sheet of bubble wrap with reflective layers on both sides, is just under 1/4" thick. The air gap is a poor conductor of both heat and sound. To apply, the 3M Super Adhesive Horvath referenced is a good product and, if used properly, will stick very well. He sort of glossed over it, but it's important to let the sprayed on layer of adhesive "tack" on both surfaces before pressing together..................same as you'd do with contact cement (which is another good adhesive to use, albeit unforgiving of misplacement). Also, good adhesive on a dirty surface won't hold. Then on top of this reflective material went a layer of thin jute for added padding. And no, I didn't have any problem with the bubbles "popping" when stepped on. I suspect the two outer layers of reflective material added strength.

Besides quieting and cooling the interior I experienced another "phenomenon" on a '40 coupe I did with the bubble material. It had cheapo glass packs I intended to replace because they sounded "tinny". Once the whole interior of the coupe was done (roof, sides, as well as floor) it changed the exhaust tone too. Not just inside as you would expect, but also from the outside. My only guess is the reflected sound from the floor pan gave less resonance, and thus a "mellower" tone. Probably wouldn't make as much, if any, difference on a pickup.