How to Quiet Exhaust Sound

by Skip Shelton
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exhaust pipe image by A74.FR Ben Fontaine from

Exhaust sounds are produced both through sound waves that travel through the air and through vibration that is transferred through the vehicle's frame body and components. Both sound waves and transferred sound must be controlled to effectively quiet the exhaust. The engine displacement also directly affects the volume of gases to be controlled. The piping, muffler, and porting of exhaust gases all contribute to the sound profile of your exhaust. Altering the primary components of the exhaust system will have the greatest effect on the sound output, though dampening the vehicle's cabin can also reduce the perceived noise level.

Step 1

Replace the existing muffler. The muffler has the single greatest impact on the sound profile of an exhaust system. Mufflers specifically designed to control sound output and volume can be installed on your vehicle to control the noise levels. Stock mufflers are usually designed to balance costs with sound control and performance. After-market mufflers are available which significantly reduce sound output without the sacrifice of performance.

Step 2

Install an exhaust tip with a sound dampening liner. Sound dampening exhaust tips, referred to as "resonated tips," contain a lining of sound absorbing materials with high surface area. Liners may be made of fiberglass or other composite materials designed to withstand the high temperature of the exhaust system. Connect the resonated tip to the tailpipe of the exhaust. Some resonated tips may decrease sound at the expense of low-end performance, such as initial wide open acceleration and response.

Step 3

Attach vibration dampening mats to the metal surfaces of the cabin and interior walls. Vibration dampening mats reduce the vibration of the metal. It is generally not necessary to cover every surface, as metal vibration can be controlled with partial coverage. Attach the vibration dampening mats to a minimum of 25 percent of the surface area of metal surfaces in your vehicle's cabin and interior. If your vehicle has a trunk, application of the vibration dampening mats to the metal surfaces will reduce interior cabin vibration transfer. Before applying the mats, remove interior seating, upholstery and trim to expose the metal surfaces.

Step 4

Install a sound blocking material over the interior surface areas. Sound blocking mats, unlike vibration dampening mats, create a layer through which sound waves are restricted. Near 100 percent coverage of the possible interior surfaces is required to create a barrier layer that is effective in restricting the transfer of sound waves. While vibration dampening mats may be used with 100 percent coverage, sound blocking mats will reduce sound wave transfer more effectively than vibration mats. Install the sound blocking material in an even layer inside the doors, under the upholstery, behind the dash and under any trim. Complete sound dampening is not possible, due to transfer of sound through window glass.

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