Depends on the cops. My old hometown they were pricks with loud exhaust. I had a T/A with a 6.6 under the hood. I ran straight pipes, they busted me a few times.
One time I was driving it with just hedders ha ha, they pulled me over and I left it running. The cop was pissed, screamed " I said to shut it off!!!" My reply was "sorry officer I didnt hear you" LOL, was funny until I went to court for that ticket