I installed some similar items I got from Menards;

-WeatherGuard (Peel-N-Seal copy) - only a few fractions of an inch thick, this provided a good stop to vibrations.
-Frost King duct insulation (Similar to Dynamat - has aluminum backing - USE GLOVES, CAN and DOES cut fingers if you aren't careful around cuts)
-Reflectex duct insuation - (tranny tunnel and floor only) This kept transmission tunnel heat out of the car.

This was installed on the:

-Door panels (inside of outside skin, inside of inside)
-Floorboards and transmission tunnel
-Behind the seats and in the trunk

Overall, before install the car was a beast as far as noise. It was loud and not quiet about it. However, post install I found the sound dramatically decreased and unless I'm boosting, driving over harsh road surface (or have bad tires) I can only hear the exhaust for the most part.

We have to pull the dash to replace it and when we do I will be adding damping material to the firewall as well. This is where the majority of the noise and heat comes from now, though I have yet to do the panel behind the seats as well (I have a vibration in there on my car too...)

Overall weight gain was probably less than 10 pounds, overall enjoyment of car with no A/C? Cross country tour approved.

 

I have a bunch of "Peel 'N Seal"-style stuff in one of my cars, it did indeed smell a bit for the first few days, but it got better over a week or so. The smell came back on hot days when the car was parked in the sun, but only for the first month or two, and I didn't find it to be overpowering. This was in the doors of a Volvo 940 to help keep the inner door parts from vibrating with the door speakers.

 

I just had this conversation with a friend who used it all over his old bronco restoration. He said after the initial off-gas on day 1 it was fine thereafter in any conditions.

 

Three laters of Fatmat from the parcel shelf to the front of trans tunnel, both doors and trunk. Most of my noise is now coming from the firewall and under the dash. One day I'll get to that too. Sometimes I forget how quiet my car is until I sit in my friends NA or someone else's miata without any sound deadener. Ive also noticed my transmission tunnel and floorboards stay much cooler in hot temps then they did before. In total added about 20lbs to the car.

 

Definitely worth doing.

I used a 3M 'Mass damping' product first. Adhesive back, very flexible and workable, about 3mm thick rubber type matting. Cabin, inside of door skins, boot floor etc.

Insulation by simonholehan, on Flickr

Then a foam/felt type matting, whole interior, up the front firewall and rear bulkhead, the parcel shelf etc.

Felt carpet 2 by simonholehan, on Flickr



As the other posters have stated - its definitely worth the effort if you have a big project with dash out etc. Small weight penalty outweight by the big improvement in comfort and road noise.

 

This guy probably has IMO the best example of proper sound deadening.

 

Snotrag, could you give a P/N for the 3M product?

18PSI, same thing, which Ensolite did you use. I ask because Ensolite appears to be a tradename and they produce a lot of different foams.

 

I cant find the original details in my email, or where I bought it from, but after a little searching I think it must have been this stuff -

PeaceMAT? XXL Car Audio Deadening Insulation 3mm 5Kg Car Heavy Layer Deadening (3m Roll) Car Audio

3M 'peacemat'

it was really nice to work with as its stretchy, so I could fit it quite well over the humps and bumps in the floor as per the picture.

 

Worked at 3M for a few years doing NVH R&D work and your setup looks very good, you may try some 1/4" foam with that 3mm mat on top, a de-coupled barrier wirks really well on the shelf behind the seats that flex and reberberate the noise bouncing around in the trunk.
How do you like this dyno?

 

Thats good to hear! Yes, very please with how it turned out. You can also just about see in those photos where I seam/stitch welded the door openings too, which I think was another incremental improvement in NVH.