Inside diameter of the muffler inlet tube.

In most cases the inlet tube, outlet tube, and the perforated tube that runs through the center of the muffler all have the same inside diameter.

Outside diameter of the muffler body.
Overall combined length including the inlet tube, muffler body and the outlet tube.

Muffler Size Selection

Generally speaking the inside diameter of the muffler is determined by the outside diameter of your exhaust system at the point where the muffler attaches.
The muffler body outside diameter and the overall muffler length are normally determined by available space and the amount of sound muffling desired. In most cases the greatest dB reduction will be achieved by installing a muffler body with the largest outside diameter and longest overall length that space will allow.

To help determine what muffler size will offer the desired performance and sound level we recommend that you consult with an engine builder who has specific knowledge of your engine and vehicle configuration. It is best that this person have hands on experience with the sound regulations and tracks that you will run at. It will also be helpful for you to observe and note the size and shape of the mufflers being used successfully by others with vehicle configurations similar to yours.

Please call us to discuss your findings; we are happy to add our input to help you make an informed selection.

Packing Material Choices

Our standard equipment high temperature lightweight fiberglass-packing material has been found to be adequate for use on the majority of high performance vehicles. Extreme sustained exhaust temperature can cause this material to deteriorate resulting in premature need for repacking; in this case we recommend use of our stainless steel “scrubble” packing. Scrubble is certainly more durable but is heavier and more expensive than fiberglass packing and should only be used when necessary. For an even longer packing rebuild interval we offer a stainless mesh material that is incredibly durable, however it is both heavier and more costly yet. We have not noticed any significant sound difference between these packing materials.

Sound/Performance Variables

Sound measurements and performance results for a given vehicle vary widely due to subtle variations.
Methods used to measure sound levels by various sanctioning bodies, racetracks, and other sound regulators are vastly different from each other and often times not comparable.
Exhaust tones and sound levels are very subjective. One person might be happy with an exhaust tone and level, a second person might find the same exhaust note annoying and loud, while a third might feel that it is not nearly loud enough.

Expected Results

Coast Fabrication offers good faith recommendations and estimates based on past experiences and theory. Because of the variables and complexities involved, adherence to a specific sound limit or performance result is not guaranteed.

Sizes/Configurations not listed

Custom sizes and configurations are available upon request please call to discuss.