My good pal Chris Vallone of Classic VW Bugs and I have had a long conversations about proper sound deadening for a vintage Volkswagen. The rear trunk area seems create the most noise, for obvious reasons.
You can use the more expensive Dynamat, but I went with a great product called QuickRoof. It’s super easy to apply, just as Dynamat and makes a big difference in sound as your pride and joy heads down the road. These photos were taking a few years back when I was restoring the interior of my ’67. As you can see, the QuickRoof goes on fantastic and at a fraction of the cost!