Aftermarket Exhaust in Hawaii
Replacing the exhaust system is legal in Hawaii, 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 Hawaii, 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. Hawaii's rule is comparative: the muffler may not noticeably increase noise above the factory-equipped level, and installing, altering, or selling louder systems is banned. Annual safety inspection applies. (§ 291-24 covers motorcycles and mopeds.)
Specific Limits
- Cutouts
- prohibited
- Muffler required
- Yes
- Catalytic converter
- removal prohibited by federal law
Frequently Asked Questions
Are aftermarket exhaust legal in Hawaii?
What are the exact aftermarket exhaust limits in Hawaii?
Street-legal aftermarket exhaust picks
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