Rosebud is a noisy car. A 14" resonator—no muffler [link], all factory soundproofing removed, lots of metal-to-metal heim joints, no headliner, etc. I installed .067" Dynamat on the floor & interior firewall and put down carpet. I installed ?" heat & acoustic damping closed cell foam under the fiberglass bonnet. I didn't use Dynamat on the door interiors, rear quarter panels or the interior roof. Dynamat is heavy and I didn't want that much weight up high. Besides, I have a carbon fiber roof and the underside looks kinda cool.

After all the soundproofing, Rosebud is still a noisy car. I can't quantify the noise reduction the Dynamat provides, perhaps it's considerable. Still, normal conversation is impossible and ear plugs are mandatory. No stereo, of course. When tunes are needed, my iPhone and noise cancelling headphones do the trick. The majority of the sound comes from the exhaust, but there's still a lot of rattles, clanks, and harmonic buzzing. I wanted a street racer, so I guess that comes with the territory.   

I put a Butyl rubber product on the floor, and Dynamat HOODLINER on the hood.




And since it is a PUP, and I did not have the roof frame, I put the butyl product on the roof before gluing material to it.

I did it and it was a night and day difference.  Prior to installing the sound deadening (Dynamat or some equivalent...  It's been too long), I could hear the sucking of the carburetor as well as every other noise under the bonnet.  After installing the deadening, it was almost a modern driving experience.  I could carry on a conversation at normal levels with my wife, instead of yelling to be heard.  Of course, it did nothing for my ability to hear her...   :-)

I used an Eastwood product. Worked a treat.

I am planning on applying some Dynamat or similar product to the fire wall and under the bonnet......has anyone tried this, and how successfull was it?