Exhaust Noise in Massachusetts
Massachusetts sets no statewide decibel limit for passenger cars, but bans any exhaust modified in a way that amplifies or increases noise — the practical test is whether it is louder than stock.
Verified against primary sources · August 2026
What the law says
MGL c. 90 § 16 requires a muffler "to prevent excessive or unnecessary noise" in good working order and constant operation, bans muffler cut-outs and by-passes, bans running a muffler with the baffle plates, screens or other original internal parts removed, and bans an "exhaust system which has been modified in a manner which will amplify or increase the noise." No decibel figure appears anywhere in the section; the registrar's inspection standards use the same louder-than-original-equipment test. A widely repeated '80 dB at 50 feet' figure for Massachusetts traces to blog sources, not the statute. A separate rule, 540 CMR 3.00, does set numeric limits — but only for motorcycles.
Specific Limits
- Standard
- no louder than the original equipment; no modification that amplifies noise
- Statewide decibel limit
- none
Frequently Asked Questions
Are exhaust noise legal in Massachusetts?
What are the exact exhaust noise limits in Massachusetts?
Street-legal exhaust noise picks
Gear that helps you mod without a ticket in Massachusetts.
Measure your exhaust at the test RPM before a fix-it ticket does.
Shop on AmazonA removable insert that brings a loud exhaust back under your state's limit.
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