The amount of noise an exhaust system produces depends on the engine installed and the exhaust system connected to the engine. Engine combustion gases exit your auto's engine through the exhaust manifold and travel to the tail pipes through the muffler. The muffler may contain chambers, baffles or sound dampening materials to modify the sound profile of the exhaust. While some sound is transferred through vibration outside the exhaust system as the exhaust gasses are expelled, the tailpipe becomes the primary point of sound wave escape.
Install a layer of sound dampening pads at the metal surfaces in the vehicle cab. Cut acoustic dampening sheets to place between the carpet, upholstery and door coverings to dampen the sound vibrations allowed to enter the cab of the vehicle. Acoustic dampening sheets also decrease external sounds such as road noise, wind and traffic sounds, and may add clarity to sounds inside the cab (such as the audio system).
Install a high-temperature exhaust wrap around the muffler and pipes. Wrap and attach (according to manufacturer's instructions) the exhaust wrap to dampen the vibrations that may pass through the exhaust into the cabin.
Change the muffler in the exhaust system. Exhaust gases converge in the muffler. If the muffler is designed to increase the sound presence of the exhaust system (such as 'glass-packs or open-pipe muffler systems), exchanging the muffler to a dampening system will reduce the sound presence of the exhaust. If a dual exhaust system is installed (with two exhaust pipes extending from the engine) allowing both exhaust pipes to enter a dual-in muffler will allow the gasses and associated sound waves to collide and be dampened or mellowed prior to exhaust. Select a muffler based on chamber design, baffling, and acoustic dampening that is designed to reduce the noise output.
Repair exhaust leaks. Exhaust leaks allow exhaust gasses and associated sound waves to escape before dampening.
Install a resonated exhaust tip. Resonated exhaust tips are internally lined with fibreglass or other sound dampening material. The resonated tip is installed on the exhaust pipe to allow the final escape of gasses and sound waves to be dampened by the lining.
If installing an exhaust wrap, be sure the exhaust wrap will not insulate the muffler beyond manufacturer recommendations. Exhaust wraps that insulate the exhaust system may raise the temperature of the muffler to the point at which the baffles degrade or smells are produced. Do not wrap the catalytic converter. Temperature exceeding specifications of may result in damage to the catalytic converter.