California exhaust law 95dB !
1) Existing law requires every motor vehicle subject to registration to be equipped with an adequate muffler in constant operation and properly maintained to prevent any excessive or unusual noise and prohibits a muffler or exhaust system from being equipped with a cutout, bypass, or similar device.
2) Existing law further prohibits the modification of an exhaust system of a motor vehicle in a manner that will amplify or increase the noise emitted by the motor of the vehicle so that the vehicle exceeds existing noise limits.
How do cops decide if my exhaust is illegal?
There are two things the state of California cares about when it comes to your car’s exhaust: How loud it is and how much it pollutes. Biannual smog testing means your car has to pass an emission test to stay street legal, but noise enforcement is a little more vague.
Per California Highway Patrol Bulletin NO.98-100: “Excessive Noise is primarily a nuisance issue rather than a safety concern, and determination of excessive noise is subjective. For this reason, enforcement personnel are to exercise sound professional judgment in making a determination of violation.”
So how exactly do they measure 95 dB?
Practically speaking it’s going to come down to the cop. If they think you sound too loud, they can pull you over and slap you with a ticket. So those of you with wide pipes might be wise to coast with your clutch in when you pass a parked police car.
What does that mean in plain English?
Before 2019, California cops could pull you over for having a loud exhaust but they would issue a “fix-it ticket.” That means that if you went back to them with a stock exhaust reinstalled within a certain amount of time, you would be free and clear.
Police are not allowed to do that anymore, and now will just give you a violation on the spot !
Cali sets the trend – what happens there spreads out across the country and often further around the world !
We all love the sound of our inline sixes whether it be burbling on tickover, running up through the torque-rich low to mid-range revs or hunting the last few horses bouncing off the red line with the rev limiter flashing.
But we must face todays’ reality that pollution is poltically incorrect and where ‘they’ can’t get us on content as our cars are classics, they can on noise-pollution !
Stock, OEM exhausts are NLA and who’d want them, especially after we’ve improved our engines – no-one wants to strangle the engines’ potentiel.
There are many choices off the shelf for after-market exhausts and many local shops will make and fit up what you want….the knack is to get the right package !
Here in Europe, the laws have been getting steadily more strict to the point where one asks oneself if it’s just a machivelian method of remowing all old cars from road, classics or not !
Most circuits have a dB limit which one must pass before being allowed on, others have certain noise detectors around the circuit pinpointing ‘abusive’ cars and certain are allowed a specific dB level throughout the year and once reached, their credit is up until the end of the year. Obviously these latter don’t want to lose valuable hiring days and so enforce strict controls !
The tendancy is therefore to lower the dB limits which may penalise many owners, in towns, cities, certain periods of the day and circuits which have remained hollowed places at which to enjoy our sportscars.
Even kept in the best condition, certain after-market exhaust lines (and I include headers in a ‘complete’ exhaust line) are just not conceived to be quiet !
Sold mostly to enhance performance, the free-flow exhausts with no intemediate silencer box and a glass-pack or expansion ‘muffler’ at the rear merely make more noise than power, completely ignoring certain physcial rules about velocity, scavenging and harmonics leading to exhaust drone.
I remember fitting a Twice-pipes line to a 6-2 header back in 1991 – I loved it and boy was it loud ; I remember being flagged down by a cop for having ‘pulled away too agressively from the sidewalk’ when I was only doing 25mp/h and having to dip the clutch to rapidly lower the engine revs whilst in the vicinity of others and late at night coming home. Great days but more complicated now……
It’s surprising when someone spends good money of their paint, nice wheels, interior, engine, brake and suspension upgrades and then refit the 20year old header connected to one the cheapest exhaust lines available online !
Your cars’ complete exhaust has as much importance as your choice of induction – twin carbs, triples, 4barrel, injection, ITBs, turbo (s) ?
Accordingly, it should be chosen with care, with the long-term in mind as no-one likes spending twice and, as I always advise, with your end use in mind !
I’m working on a guide to understanding exhaust mechanics, something simple to read albeit complete. I believe that there isn’t enough unbiased information out there to properly advise users.
Db limits of my mufflers using a resonator and measured on a Rebello L32 with triple 44 Mikunis !
Later on this year, I’ll be adding a fifth muffler type to my range ; the ‘Hako’, a horizontal twin-exit muffler which can expected to sound similar to my JDM.
My Street and Trackday share the same exterior form, the Street being baffled whereas the Trackday is an expansion box as per the Classic, JDM and Hako.