Aftermarket Exhaust in Arizona
Replacing the exhaust system is legal in Arizona, but a muffler in good working order is required and cutouts or bypasses are prohibited. There is no statutory 'no louder than stock' rule — the standard is that the exhaust must not produce excessive or unusual noise.
Verified against primary sources · August 2026
What the law says
Replacing the exhaust system is legal in Arizona, but a muffler in good working order is required and cutouts or bypasses are prohibited. There is no statutory 'no louder than stock' rule — the standard is that the exhaust must not produce excessive or unusual noise. Removing the catalytic converter is prohibited by federal law (Clean Air Act § 203) regardless of state rules. Arizona state law separately requires emissions control devices on 1968-and-newer vehicles, with civil penalties starting at $100. Phoenix and Tucson require emissions testing.
Specific Limits
- Cutouts
- prohibited
- Muffler required
- Yes
- Louder than stock
- not addressed; excessive noise standard applies
- Catalytic converter
- removal prohibited by federal law
Exceptions & Exemptions
Must not exceed noise levels that would be unreasonable under normal operating conditions. Muffler must be in good working order and constantly operated. Catalytic converters cannot be removed or bypassed on vehicles originally equipped with them.
Frequently Asked Questions
Are aftermarket exhaust legal in Arizona?
What are the exact aftermarket exhaust limits in Arizona?
Are there exceptions for aftermarket exhaust in Arizona?
Street-legal aftermarket exhaust picks
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