sound deadening?

I am soon going to start to put the carpet back into my Mk1 GTi when i had it painted i have the black Bitumen in the front foot wells removed.
Now i have new foam to go under the carpet but will i need to put anything down first or will just the foam and carpet be ok?

Thanks

I lot of folks over here are putting Dynamat down as a soundproofer under the foam.  They claim it quiets it down 100 percent.

I'd 2nd the Dynamat roll, used it on my '64 beetle rear bulkhead. Cut down on top-end engine noise loads.

After lots of searching for some sound deadening, I've just bought some "silent coat 2mm" to use in the caddy, as it's supposed to be similar to, but is about a third of the price of, dynamat.

All it is doing is adding 'mass' to the panels to stop vibrations, or to change the vibrations from really annoying ones to lower frequencies, and it has some good reviews (other than just on the website selling it)