I finally had to do something about the noise, My sound barrier Options

[DNHunt]

I found a product called Quiet Zone made by a company called Ixos. It has a 3 mil aluminum layer with a 1.5mm visco-elastic layer. They put it directly on painted metal but, I still have visions of rust repair so I came up with a different idea.

I put a 2 mm form layer on the 2nd layer. The gray stuff is the visco-elastic layer and the green is the foam.

[IronHillRestorations]

Looks like a good choice for sound deadining material. I've used a few different products by B-Quiet ( bquiet.com ).

Honestly Dave, I agree with JP here. I think it's a mistake to try and attach that with self adhesive velcro. It's going to come off and smother the cooling impeller, and I don't know why but it will be at the worst possible moment.

What I've done is to mechanically fasten it to the firewall. I've done this with a few cars and it's turned out pretty good. I drill holes in the firewall and flare them inward with a punch (to give some extra metal to thread) and then thread the holes for a m6 cheeshead screw. Then you use a fender washer behind the m6 screws and it holds great, and looks very acceptable.

Another thing I've done is to use some high quality silver mylar tape around the perimeter of the sound mat, to help keep out moisture.