Rog,
I have used Dynamat and a product called HEI Insulation. I picked it up from Summit with the Dynamat. I used 5 sheets of 1m x 1m stick on heat shield ( just enough ) and two large boxes of Dynamat. I went over board with both as the car was BLOODY HOT to drive. I also insulated under the tunnel with another HEI HI TEMP product ( 1700 DEG HEAT WITH 450 DEG SELF ADHESIVE GLUE ) very expensive ( $280 just to do the tunnel
) the Dynamat and HEI product delivered was around $600 from memory. I also had the best heat resistant underlay installed AND carpet. I HPC coated the entire exhaust system.
Did it work????? As I type the car is gettting the A/C gassed and working correctly for my trip to Tassie next Month
.....
It certainly did help, dont know by how much but I can say I didn't leave any thing to chance. Its just a hot car to drive, probably similar to a GT40.
STIFFY