After adding a floor to the rear of the car I thought it would be the perfect time to add some sound deadening and heat insulation! I picked up this tar-based insulation which is extremely heavy and quite easy to work with from Amazon. Laying it down wasn't too much of a hassle!
And a cat! He was helping me out by doing absolutely nothing. The deadening worked like a charm and I am ready to test it out on the road... eventually. I also purchased more to do the front of the car should the carpet ever get pulled up.