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New Hampshire Exhaust & Muffler Laws (2026)

Info: Your vehicle needs a muffler in good working order, and cutouts, bypasses (which route exhaust around the muffler), and straight-pipe exhaust are prohibited.

InfoVerified Jun 19, 2026

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Your vehicle needs a muffler in good working order, and cutouts, bypasses (which route exhaust around the muffler), and straight-pipe exhaust are prohibited. New Hampshire sets no decibel limit for cars — the decibel limit in 266:59-a applies only to motorcycles (N.H. RSA § 266:59).

Official source: gencourt.state.nh.us →

General legal information, not legal advice — verify important decisions with a licensed attorney.

Exhaust & Muffler in states bordering New Hampshire

The same rule in each neighboring state LawLert has verified, from that state’s own official source.

MaineInfo
Your vehicle needs an adequate muffler, cutouts and bypasses (which route exhaust around the muffler) are barred along with changes that increase noise, and a car over 95 decibels, measured by the SAE J-1169 test, is in violation (Me. Rev. Stat. 29-A § 1912).
Verified Jun 19, 2026 · Source: legislature.maine.gov · Full Maine rule →
MassachusettsInfo
Your vehicle needs a muffler in good working order that prevents excessive noise, and cutouts, bypasses (which route exhaust around the muffler), removed baffles, and noise-amplifying exhaust are banned. Massachusetts sets no fixed decibel limit (M.G.L. c.90 § 16).
Verified Jun 19, 2026 · Source: malegislature.gov · Full Massachusetts rule →
VermontInfo
Your vehicle needs a muffler with baffle plates, and gutted mufflers, cutouts (which route exhaust around the muffler), straight pipes, and noise-amplifying changes are prohibited. Vermont has no decibel limit on the books (23 V.S.A. § 1221).
Verified Jun 19, 2026 · Source: legislature.vermont.gov · Full Vermont rule →

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