Id go with the Bituthene. Pretty much the same as Dynamat,,,but youll save yourself a bunch of $$$. I used something similar,,,called "quick roof" a 25 foot roll was less than 10 dollars. Has the foil face and a very sticky backing. Be sure to at least wipe down the area with a damp rag to remove all dust,,dirt,,etc for a good bond.
I did everywhere I could fit my hands into. Youll be surprised at the difference it makes. Don't waste your money on the Dynamat name.
Good Luck,
