I agree this behavior is definitely risky, but may be worth the risk for some people. Over the years I've had several experiences with neighbors that like to make noise. I try to pick my battles and only said something when the behavior was exceptionally bad. The times when I decided to talk to them about it, like an adult, never once had anyone said, "Oh, I didn't realize my exhaust noise was such an issue. I'll take care of it. Thanks for talking to me directly." The universal response is, "go F*** yourself!" So there is your answer for anyone asking the question, "Why not just go talk to them?" Consider the mindset of people who behave this way: they spent extra money, often lots of it, to make their exhaust super noisy, and they really like it. So, talking doesn't help. And sadly, calling the police rarely helps.
It's fine to have a noisy exhaust as long as you are not romping on the throttle in residential neighborhoods. Have some respect and consideration for other people's homes. If you want to make noise, go out on the open highway or find an industrial/commercial area and make all the noise you want... do it anywhere people are not trying to sleep or enjoy some peace in their homes. But here's the rub: people with loud exhausts are desperate for attention and they aren't getting much attention in industrial or commercial areas. So we get to be awakened from our peaceful sleep. Thanks.