SEMA Proposes Compromise to Michigan Exhaust Noise Bill


Working with bill sponsor Representative Doug Geiss, the SEMA Action Network (SAN) is proposing a compromise to legislation (H.B. 5726) that originally sought to prohibit motor vehicle repair facilities from modifying an exhaust system to “produce noise in excess of OEM stock decibel levels.” The bill carried a fine of $10,000 for each violation. While it is unlikely that there is time in the current legislative session to enact a compromise into law, it could serve as the template for future discussions on this issue by the legislature.

Many other states have established noise limits for modified exhaust systems based on an easy to administer test standard. These limits allow vehicle owners to prove compliance by an objectively measured fair and predictable procedure. In California, for example, a SAN-supported provision is made for the testing of vehicle exhaust noise to a standard adopted by the Society of Automotive Engineers (SAE) with an established noise limit of 95-decibels (SAE J1169). Under the SAE standard, a sound meter is placed 20 inches from the exhaust outlet at a 45 degree angle and the engine is revved to three quarters of maximum rated horsepower. The highest decibel reading is then recorded. Automotive hobbyists and related industry members have found this to be a reasonable and fair approach.

We are proposing that Michigan abandon H.B. 5726 in favor of a reasonable noise limit for modified systems which can easily be tested and administered. We will keep you updated on our progress.