Funny story:
I was snowmobiling with a group near Newberry, MI last week, topping off with fuel at a VERY busy gas station with sleds, cars, people everywhere, lines for the pumps. Then 2 sleds pull in with pipes that would make your ears bleed. All conversations stopped (impossible anyway), and you could see the entire place just glaring at these two sleds that were too stupid/oblivious to even shut them down while they were idling waiting their turn at a pump. They even brapped their throttles a few time since they seemed to like the attention.
FINALLY, an elderly lady (non-snowmobiler, or maybe ex-snowmobiler) who was filling her car hung up her pump, walked very slowly with her cane about 50 feet over to these two people, rapped her cane on both their kill switches to shut them down, and proceeded to yell them the riot act. Swinging her cane through the air yelling things about how stupid and inconsiderate they were, she was gonna call the cops, those things should be illegal, etc, etc etc. The two sledders were dumfounded and didn't say anything. I'm sure if I were to try to do what she did I'd end up starting a fight...but waddayado when it's an old lady with a cane?!
So the old lady finishes up her speach and starts walking back to her car, and the ENTIRE GAS STATION ERUPTS IN APPLAUSE! Sledders and non-sledders alike. Many other sledders approached the lady and thanked her for saying what needed to be said, apologized on behalf of the morons, and helped her back to her car. She was smiling and grateful and said thank you for bringing so much business and economic support to her small community but we should all band together and get the loud sleds banned from the trails.
Several agreed with the lady that they'd do so. A few other sledders approached the loud sled and I feared a fight was going to start...but I'm proud to say it all stayed clean and professional. They just walked up with pen/paper, wrote down registration numbers/sled descriptions of the loud sleds, and informed the owners that they were going to give the info to the police so they could try to make their vacation miserable. Good idea, I thought.
So now that's my practice: If you have a sled that I feel is too loud and I see you walk into a bar/gas station/motel room. I'll wait till you're out of sight and I'll "admire" your sled without touching it, and just write down your registration number, location, and sled description and quietly report it to the police and/or DNR at my earliest opportunity. So now the cops are actually looking for you and everyone in your group, and they're not just stumbling on you by chance. My goal is to ruin your ride because of your noise level. And I will not stop until my goal is accomplished. This is not a game of specific decibles/laws/rules, it's a game of common sense. If your sled is so loud that everyone stares at you, it's too loud.
SPREAD THE WORD. LOUD PIPES CLOSE TRAILS. REPORT THEM to the authorities, turn up the pressure on them, and lets get them off the trails permanantly. Make rules in snowmobile clubs banning loud pipes. Refuse to ride with people who have them. Write to the snowmobile magazines and manufacturers that we want quieter sleds. People who have loud pipes are NOT true snowmobilers. Let's let them know what true snowmobilers think about them.