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Old 01-18-2016, 05:48 AM   #6
Keysdisease's Avatar
City: South Florida
Country: USA
Join Date: Sep 2014
Posts: 675
The right way to do this is to have a new lagging blanket made. These are typically sewn by companies that specialize in marine exhaust. This will thermally insulate the muffler from the trunk, be removable for service, and last a long time.

The trunk should also be insulated, both thermally as secondary protection and acoustically for noise reduction.

The three most popular incombustibles for this are mineral wool (rock wool), fiberglass and ceramic.

Mineral wool should be available from any industrial insulation supplier because its common in restaurant and commercial use. It's available as a blanket or semi-rigid board. The appropriate fiberglass should be available through marine outlets, ask to browse a catalog or go online. Ceramic is the latest and greatest and expensive.

As an acoustic barrier that's incombustible lead would be the best choice, in either a 1 or 2lb sq ft sheet.

With insulation, more is better.

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