Engine noise

When I first bought my MH it was loud and hot on a hill climb. I added a 1/2 layer of insulation that I bought at HD or Lowes. It was inexpensive and worked well. I used Weldwood contact adhesive to bond the insulation to the factory insulation which was a bubble wrap material with foil on one side and about 1/4 thick. The new material was made from a jute felt and foil on the eng side. There was a huge reduction in noise and heat for about $20 of materials. Lead sheeting would be about the best material to use if cost was no object or you had a free or inexpensive source for it. We used to use a material called Acousticore where I worked which was a 1/2 in thick honey comb core with a fibrous material stuffed inside the cells of the core but found that .050 sheets of lead worked much better.