Aftermarket Exhaust in Wisconsin
Replacing the exhaust system is legal in Wisconsin, but a muffler in good working order is required and cutouts or bypasses are prohibited. Modifications that make the exhaust louder than the originally installed muffler are specifically prohibited.
Verified against primary sources · August 2026
What the law says
Replacing the exhaust system is legal in Wisconsin, but a muffler in good working order is required and cutouts or bypasses are prohibited. Modifications that make the exhaust louder than the originally installed muffler are specifically prohibited. Removing the catalytic converter is prohibited by federal law (Clean Air Act § 203) regardless of state rules. Wisconsin also bans flame-igniting devices. Emissions testing applies in seven southeastern counties.
Specific Limits
- Cutouts
- prohibited
- Muffler required
- Yes
- Louder than stock
- prohibited by statute
- Catalytic converter
- removal prohibited by federal law
Exceptions & Exemptions
Muffler must be in good working order and prevent excessive noise. Catalytic converter required if originally equipped. Sound level must not exceed reasonable limits.
Frequently Asked Questions
Are aftermarket exhaust legal in Wisconsin?
What are the exact aftermarket exhaust limits in Wisconsin?
Are there exceptions for aftermarket exhaust in Wisconsin?
Street-legal aftermarket exhaust picks
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