After long time thinking how to go on with heat /noise insulation in the engine bay, I decided to use cork as first layer. It is lightweight, has good damping properties, impact and airborne noise. Took a long time to find a good quality (not that floor house building stuff from Homeworker shops). The one I use is for railway wagons as damping material. Much smoother and finer pieces, self-adhesive for better aplication. To get an more even surface for the final layer of Aluminum coated FG I "filled-out" several slots with cork too.
Long story short said, not my favourite kind of work, difficult to transfer the 3D shape on the flat cork sheets...
Here is how it looks right now:
