Aftermarket Exhaust in Indiana
Replacing the exhaust system is legal in Indiana, 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 prohibited.
Verified against primary sources · August 2026
What the law says
Replacing the exhaust system is legal in Indiana, 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 prohibited. Removing the catalytic converter is prohibited by federal law (Clean Air Act § 203) regardless of state rules. Indiana exempts vehicles 25 years and older from the state catalytic-converter requirement (IC 9-19-8-0.5), though the federal ban still applies. Lake and Porter counties require emissions testing.
Specific Limits
- Cutouts
- prohibited
- Muffler required
- Yes
- Catalytic converter
- removal prohibited by federal law
Exceptions & Exemptions
Must maintain original equipment catalytic converter or EPA-approved replacement. Muffler required to prevent excessive noise. Sound level must not exceed reasonable limits that could disturb the peace.
Frequently Asked Questions
Are aftermarket exhaust legal in Indiana?
What are the exact aftermarket exhaust limits in Indiana?
Are there exceptions for aftermarket exhaust in Indiana?
Street-legal aftermarket exhaust picks
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