Peter J here..
Yes, I applied the thin (5mm?) Dynamat to the interior of the Roadster, including the doors, floor, rear bulkhead and the transmission tunnel. It made a significant difference to road noise and a little unexpectedly, it massively reduced heat transfer into the footwells.
I have an info sheet, based on an article in Miscellany. Pop me a PM with your e-mail and I'll send it on to you.
It took me about 4 days in total, spread over a few weeks. The seats came out and I made angled spacers, as reported by others, they allow the seat adjusters to work properly.
So, have I applied Dynamat to th Aero S4 Chassis on the Plus 8?
No, the car is already much quieter than the Roadster and there is no heat sink into the cockpit.
BUT on the basis that you cannot have too little NVH it is on the list of "Things to do".
