* California limits exhaust noise to 95 dBa: http://www.californiacarlaws.com/exhaust-noise/
* Colorado has a subjective standard "prevent any excessive or unusual noise" https://law.justia.com/codes/colorado/2016/title-42/regulati...
* Connecticut has a pretty complicated scheme depending on the vehicle's weight and age, as well as the road surface: https://www.cga.ct.gov/2009/rpt/2009-R-0205.htm
* Delaware has a subjective standard: "muffler in good working order and in accordance with manufacturer's specifications and in constant operation to prevent excessive or unusual noise." https://law.justia.com/codes/delaware/2015/title-21/chapter-...
There are, of course, laws about other sources of noise too. Ask any college kid.
The level of enforcement for this has to be something like zero....
The level of enforcement for this has to be something like zero....