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Wisconsin Exhaust & Muffler Laws (2026)

Info: Your vehicle needs an adequate muffler operating at all times, and cutouts and bypasses (which route exhaust around the muffler) are prohibited, along with changes that amplify noise beyond the factory muffler.

InfoVerified Jun 19, 2026

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Your vehicle needs an adequate muffler operating at all times, and cutouts and bypasses (which route exhaust around the muffler) are prohibited, along with changes that amplify noise beyond the factory muffler. Wisconsin sets no fixed decibel limit (Wis. Stat. § 347.39).

Official source: docs.legis.wisconsin.gov →

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

Exhaust & Muffler in states bordering Wisconsin

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

IllinoisInfo
Your vehicle needs an adequate muffler and exhaust so it doesn't make excessive or unusual noise, and cutouts and bypasses (which route exhaust around the muffler) are prohibited, as are changes that increase noise. Illinois sets no fixed decibel limit (625 ILCS 5/12-602).
Verified Jun 19, 2026 · Source: ilga.gov · Full Illinois rule →
IowaInfo
Your vehicle needs a muffler in good working order so it doesn't make excessive or unusual noise, and muffler cutouts and bypasses (which route exhaust around the muffler) are prohibited. Iowa sets no fixed decibel limit (Iowa Code § 321.436).
Verified Jun 19, 2026 · Source: legis.iowa.gov · Full Iowa rule →
MichiganInfo
Passenger vehicles can't exceed 82 decibels above 35 mph, or 76 decibels at 35 mph or below, measured at 50 feet, and cutouts, bypasses (which route exhaust around the muffler), and amplifiers are banned (MCL § 257.707c).
Verified Jun 19, 2026 · Source: legislature.mi.gov · Full Michigan rule →
MinnesotaInfo
Your vehicle needs a muffler in good working order so it doesn't make excessive or unusual noise, and muffler cutouts, bypasses (which route exhaust around the muffler), and similar devices are banned. Minnesota sets no decibel limit in statute (Minn. Stat. § 169.69).
Verified Jun 19, 2026 · Source: revisor.mn.gov · Full Minnesota rule →

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