Srt-68 Barracuda
Not to knock what you are using but it is not the same stuff as hush/dyna mat. The sound deadening quality is not the same nor is the ability to block the heat as well. I looked at that product as well.....cool no doubt.
That being said for $45.00 its a great alternative and I am actually going to supplement my hush mat with something like this....foil on one side and thick 1/2" felt on the other. Also saving $300.00 for something you really need is just smart economics.
As far as putting it in the doors the only caveat I see is that there is a real and dangerous possibility of water getting behind the product and getting caught thus, over time causing rust issues later.....I have seen it and that is why I chose to use spray undercoating in the doors vs. stick on....just to be safe.
Just an observation.
Mop