Exhaust Noise in Illinois
Illinois does set numeric limits — just not in the Vehicle Code. Pollution Control Board rules cap passenger cars at 74 dB(A) at 35 mph or less and 82 dB(A) above that, measured at 50 feet, and the Vehicle Code separately requires a muffler and bans amplifying modifications.
Verified against primary sources · September 2026
What the law says
625 ILCS 5/12-602 requires a muffler in good working order, bans cutouts and bypasses, and bars modifications that amplify noise above the originally installed muffler. The numeric limits live in the administrative code: 35 Ill. Adm. Code 902.120 caps vehicles of 8,000 lb GVW or less at 74 dB(A) on highways posted 35 mph or less (76 on grades over 3%) and 82 dB(A) above 35 mph (85 with snow tires), measured fast-response at 50 feet from the lane centerline, enforced under the Environmental Protection Act.
Specific Limits
- Measured at
- 50 feet from the lane centerline
- dB limit cars
- 74 dB(A) on roads posted 35 mph or less (76 on >3% grade); 82 dB(A) above 35 mph (85 with snow tires)
Frequently Asked Questions
Are exhaust noise legal in Illinois?
What are the exact exhaust noise limits in Illinois?
Street-legal exhaust noise picks
Gear that helps you mod without a ticket in Illinois.
Measure your exhaust at the test RPM before a fix-it ticket does.
Shop on AmazonA removable insert that brings a loud exhaust back under your state's limit.
Shop on AmazonAs an Amazon Associate, Is My Mod Legal earns from qualifying purchases made through these links, at no extra cost to you. We only recommend gear that helps you stay street-legal.