Originally Posted by
kung fu jesus
Tim,
As an experiment on my NA, I sprayed undercoating on my rear parcel shelf cover...the flimsy tin cover held down with a number of 10mm bolts. The smell was bad, but if I were to do it again, I would use sheeting like you used. Just a heavy layer of coating on that reduced a noticeable amount of road noise from the trunk area.
Also, on my NB, I had removed a portion of fluff mat Mazda puts on the rear bulkhead. The portion I removed was behind the passenger seat. That actually increased the noise in the cabin considerably. I think if I were trying to reduce noise like you are without adding a LOT of weight, the front and rear bulkheads would be a priority to me. The 'tunnels' on the sides of the car that run from behind the seats to the trunk could also be stuffed without detriment. I would think something simple like throw pillows would do a lot to cut the noise in the cabin that is channeled into the cabin through those.
Also, a hardtop with a liner would be a lot quieter than a softtop.