Interesting Peter. If you cover the gearbox cover with Dynamat you may have problems fitting the leather cover back on. There is a 1/4" or so of matting already applied to the inside of the cover as standard.
I was concerned about that, but based on a trial using corrugated card, the same thickness as the Dynamat, on each side of the gearbox casing there is enough room.
Peter
I will eagerly wait to hear on your report of sound improvement, with the roof off and on. I have investigated this myself, and have to admit to having some sound insulation to fit under the leather covers next to the door and some sound/heat shielding to go at the bottom of the foot wells (the stainless exhausts on Rosie generate a lot of heat onto the footwells), I have also considered covering the floor and rear boards behind the seats with dynamite and around the gearbox casing (no insulation at all on my +8 around the gearbox). I have done nothing on this to date as you already said it is a major exercise requiring seats out and lots of fiddly bits. One area I am not sure if you've considered is the boxing immediately behind the doors, on my car they are empty boxes that basically act as a resonating boxes just above the silencers, so I was intending to fill them with a waterproof sound matting to stop this.
