Vehicle Mod Laws 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.

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Hawaii sets no statewide decibel limit for passenger cars. A muffler in good working order is required, exhaust may not produce excessive or unusual noise, and cutouts or bypasses are prohibited.

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Smoked or tinted film on headlights and taillights is illegal in Hawaii. Headlights must emit white light and taillights must show red at the required visibility distance, and tint that dims or discolors them violates those requirements.

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Hawaii plates must be displayed entirely unobscured, and plate covers are already restricted — from January 1, 2027, Act 12 bans every cover and shield outright, clear ones included, at no less than $1,000 per day.

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Hawaii caps bumper height at 22 inches for passenger vehicles, rising by weight class to 29, 33, and 35 inches, measured from the ground to the highest point on the bottom of the bumper.

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Hawaii requires no cover and sets no auxiliary-lamp count. Its limits are output and use: headlamps white and under 2,400 apparent candlepower, spotlights barred in cities and towns and off within 200 feet of approaching traffic, and blue lamps banned down to mere possession.

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Hawaii has no minimum-height rule for lowered vehicles — its height law works from the top: bumpers cap at 22 inches on passenger vehicles (29/33/35 by weight class for heavier ones), the frame rail may not exceed the bumper, and the body may sit no more than 3 inches above the frame.

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Underglow is legal in Hawaii, including while driving, subject to color and flashing limits: Front-visible light must be white or amber and rear red, with no flashing; blue is banned on all vehicles.

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Hawaii's safety inspection rejects a vehicle unless the fenders cover the entire width of the tire tread viewed from above and cover the tire from vertical to 75 degrees rearward — so tires must effectively stay covered.

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Transparent sun-screening film is allowed along the top edge without encroaching on the AS-1 portion — or, on windshields with no AS-1 marking, no lower than 4 inches from the top. Because the material must be transparent, a printed or opaque banner is not legal in Hawaii — only a clear tint band.

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Front side windows: minimum 35% VLT. Rear side and back windows: any darkness.

Limits, exceptions & statute →