For those of you that have older Mercedes based A class campers you will know about engine noise issues. When I had the interior makeover done I got them to make me an engine/dog kennel cover out of leather which I must say reduced the engine noise quite a lot. To reduce it further I am thinking along the lines of stapling either acoustic foam or carpet underlay onto the underside of the plywood dash, above the engine. You know, the bit between the windscreen and the original van dashboard. I did have a new dash carpet made at the same time as the makeover, but looking up from above the engine its just marine grade ply with some underseal painted on it. I am thinking that this is amplifying the sound similar to a drum. I already have loads of carpet underlay in the attic so is there any reason why this cant be used. I know about the lead noise killer blankets, but dont fancy the outlay for them.