After researching this. The places that sell these insulators call them heat and sound insulation. After running mine w/o for a while the underhood paint looks faded where the supercharger is located. I put mine back on recently. While I didn't notice any sound difference the top of the hood doesn't get anywhere near as hot as it used to.
Back in 83 a friend bought a new mitsubishi starion turbo. At that time they didn't come with hood insulators. He had to have his hood repainted 3 times due to the heat from the turbo. The dealership finally told him he should pop the hood after parking to let the engine cool down to prevent anymore paint damage. I'm sure the paint wasn't as good in 83, but this still has me wondering.
When I put my IC on ,the insulator may come back off, since my hood paint doesn't look that great anyway.
