This post is only semi-technical I guess. I as I start to plan the interior teardown of my '70 Cuda and I find myself on the fence with this matting I bought.

1) From an investment or even show standpoint, is having sound deadening material under the carpet a bad thing? I was intending to only use it where the carpet jute is lacking and in key spots on the dash.
2) Do the deadening mats create any additional problems to the metal? Do they leave little tar patches or are they impossible to remove?

I am really on the fence here. I like the engine/road noise but I don't like the squeaks so I was going to use it sparingly for some dash contact points (plastic on metal, etc). I have seen people line their doors, firewall, floor, etc but I think I value "original" more than "quiet".

just my here.
if you are building a 100 point show car don't use it.
if you building a really nice driver car I highly recommend using it.

there are a LOT of different sound deadeners.
the type I have used and seen others use is a tar based self sticking adhesive pads, some are foil backed for heat resistance. this type works great, it's almost impossible to remove. most sound deadening materials will be difficult to remove.
in my opinion is it won't make the car worth less. it won't make your car worth more but it will make you car much easier to sell because the car will be a much nicer car to drive.

I agree with Mr T2U

If you don't like the squeaks, creaks, and rattles, then install subframe connectors. They will do more to eliminate the noises then sound deadener will do to reduce it.

Thanks all. The squeaks and pops I have are in the current dash. Once I strip and coat the dash frame, I may use some small strips of deadened to get the dash parts to align better and to prevent dash noises.

The floor is pretty quiet so I think I will go ahead and use some matting where there is no jute like along the hump, under the rear seat and a little higher up on the firewall.

I am using the foil-backed GT Pro matting. I was concerned about the "impossible to remove" factor so I think I will just use it where it would be best served instead of everywhere.

I really appreciate you guys and your time and opinions.

Thanks for the note. As far as heat is concerned, I assume that the heat is coming in from the pipes below, the hump above the transmission and the firewall up front.

I assume it is the aluminum coating that will help reduce that especially where the jute is absent.

Very nice! Thanks for the photos.