CA Vehicle Code KIKAN (my nickname lol)

(a) A person shall not modify the exhaust system of any vehicle who’s gross weight is 5,999 lbs or less, excluding motorcycles, in a manner that will prevent the vehicle from passing California Smog testing.

(B) All vehicles shall be equipped with adequate and well maintained catalytic converters and mufflers to limit any sort of air pollution as so required by state smog inspections. 

(c) Any sort of exhaust bypass, cutout, whistle tip, or other similar devices are not permitted on California highways.

CA Vehicle Codes 27150 and 27151 target noise rather than emissions. We live in a crowded city with millions of vehicles. We need to be considerate and come to a compromise to keep our air clean. Above is what I am proposing. In a nutshell, leave your catalytic converters alone and you can do as you please after that. I think we can all get behind this. It also removed the noise limit so we don’t have to be scared around police officers. Because from experience, the vast majority of them do not care how loud your car is.