I went the opposite way, I had some sound deadening material (6mm black sticky stuff with a shiny aluminium face) left over in the garage, decided to stick this on the bonnet under the insulator. Its quite heavy (would be I suppose to deaden the sound). Replacing the insulator was interesting dropped a couple of clips, so had to get replacements. It does make a difference to the amount of noise in the cabin though, so pleased with the result.