I had a shitbox with a piece of pipe I welded on after the exhaust fell off once (it was fully legal and passed state inspection). I got pulled for driving the speed limit and the cop told me I was breaking noise ordinance. I ask which ordinance and all they did was fume at me that they can't "name it off the top of their head". I'm sure the cop never pulled over someone in a giant diesel truck or a 100k sports car for making noise.