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What You Need To Know About The New California Noise Law And Aftermarket Exhausts

nissan skylineThe internet has been very active recently with rumors of all sorts regarding a change to the way California enforces the excessive exhaust noise laws regarding motor vehicles. Bloggers, YouTube video makers, forum pundits, and social media commentators are all up in arms about the state, California Highway Patrol, and local police forces coming for their mufflers and cat back systems, and slapping them with $1,000 fines. We reached out to anyone and everyone we could find to try to get to the bottom of this for you, including representatives from Borla, Magnaflow, DynaMax, CHP, AAA, SEMA and even a local legislator in West Virginia who helped draft the law that California’s was based on. What follows is what we have found so far, and it will get updated when we know more.

Almost none of the rumors are true. You can still install aftermarket exhaust systems without breaking the law, and if you do get pulled over for your car being loud, contrary to widespread claims, it is not an automatic, mandatory $1,000 fine, and you won’t have to put your car back to 100% stock.

The only law pertaining to exhaust system noise that changed in California on January 1st, 2019, is that now it is a fine and an order to visit a referee station to have the noise level measured. Instead of a fine, before the first of the year, you would pay a filing fee of $25, and get an law enforcement authority to sign off that it had been fixed/quieted.

The law governing what is excessive noise has not changed and dates back to 2003, it is based on a simple test done at idle speed with the car parked. A dB sound meter (you can download an app for your phone) about 20″ away from the exhaust tip, and 45 degrees away from directly behind it, can read no more than 95 dB. This law was written and passed in several states (not just California) with input from SEMA and aftermarket exhaust manufacturers to replace a vague law that dated back to the 1970s. SEMA Director of Government Affairs Steve McDonald had this to say about it when it passed:

“The new law forces compliance with an objectively measured standard in a fair and predictable test. Through this procedure, cited motorists who drive vehicles legally equipped with modified exhaust systems can confirm that those vehicles comply with California’s exhaust noise standards. For years, the enforcement policy used by police officers deemed nearly all exhaust system modifications illegal, even where the noise levels were not excessive or unusual. That policy left exhaust system manufacturers, dealers and their customers without recourse.”

quad exhaust tipsUnder the old system, you would be given a “fix-it” ticket based on the whim of the officer issuing the citation. There was no official testing procedure or sound limit that was deemed “quiet enough” by law. If you failed to correct the violation and file the paperwork within 30 days, a “failure to appear” ticket would be issued which carried a fine of hundreds of dollars and a mandatory court appearance.

The law now in place set a standard of 95dB for a car at idle and has been on the books since 2003. This is also the federal DOT standard that motorcycles have been required to pass for decades. If you do get a ticket you are directed to take your car to a “referee station” to perform the sound test and give you a certificate of compliance. The certificate, filed with the court, will negate the citation, and it is not a moving violation so there are no points involved. It is assumed that if you test and do not meet the noise limit you will have to pay the fine, but it is not known if you can pay the fine and not fix the noise violation.

The fines start as low as $25 and can run to nearly $200, not including the fee you would pay the referee station to test your car for compliance.

We downloaded a free dB sound meter for an Android smartphone and tested the loudest car we had on hand, a Camaro ZL-1 with aftermarket system. The fifth generation Camaro registered well below the legal limit at idle (81dB), and even when revved to a reasonable degree was well within compliance (89dB). If you wish to test your car, download an app and follow this procedure.

Here is the official FAQ from SEMA debunking many of the rumors people have been spreading. The referee testing instruction to those who have gotten a ticket is here.


It seems that what many people are really worried about is a referee station finding other parts that do not comply with smog regulations. We reached out and this is what the Bureau of Auto Repair (who run the referee program) told us:

We have calls in to other people in authority, and we will update this when and if we get more information.

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