I used a dynamat clone from amazon called Noico. It was a lot cheaper and the only difference seemed to be that the tin foil was thinner. I covered the floor, trunk, wheel wells and everything else I could stick it too. I put it behind the door panels too. Saw them do similar thing on Graveyard Cars. I used aluminum furnace tape from Lowe’s to cover seams as it is cheap. The stuff doesn’t adhere permanently till it goes through a few temperature cycles, then it is really stuck. It really quieted the car down a lot. I still like loud cars, but I am old enough I prefer the loud on the outside.
People use a lot of different things. Furnace duct insulation, shoddy pad, carpet pad, & all kinds of clever stuff. If you search forums here and the internet you will find a lot of info.
