Many states seek to make things a little quieter by passing laws on noise emissions. A recent state to jump into the fold where the motto must be "We need law for that" is California. Already federal law for sound limits beginning in 1983 require that all street-legal motorcycles be limited to 83 decibels and a 80-decibel limit imposed beginning in 1986, measured with a ride-by test.
The problem with this law is not limiting sound but the inclusion of "That a label be affixed onto the motorcycle or exhaust emission system indicating that the motorcycle or exhaust emission system meets the noise emissions standards". I can just see the poor officer who is working traffic stop and has been told upper management he must start checking for this label. Where is the officer supposed to look for these labels?
I have a thought: write another law stating where the label should be placed. Now the label is not easy to see, no problem write another law, include what color the label should be, the font size and the letter spacing.
The point is there should be a single standard to see if a motorcycle is in noise level compliance, the SAE J2825 Motorcycle Sound Test is a one that is uniform and easy to interpret as shown in this video: