No, that is most definitely not what the discussion here was about. Noisy motorcycles don’t roll off the assembly line. No bike from Harley Davidson comes with straight pipes. There is litte doubt the bikes people in this very thread are referring to were running illegal exhausts. Nearly all of the people I know with Harleys have illegal exhausts. I once had slip-ons on a Harley that were not that loud compared to many bikes I hear, but they were not legal.If you are referring to illegally modified vehicles then why is that even part of the discussion? They are already illegal - in parks or on any other highways. Surely the discussion here was about noisy, but legal, motorcycles.
Furthermore, the sound from loud motorcycle pipes propagates quite far:
Motorcycles Rev Up Noise Fears In National ParksTrevino and her team are now recording audio at more than 70 national parks around the country. They're trying to get a handle on just how noise polluted the parks are. They found that motorcycles can sometimes be heard up to 18 miles away. That noise can make it harder for animals to hear predators or listen for prey. Elk and songbirds have trouble finding mates. Trevino says that while there are plenty of blind vertebrates, there aren't any deaf ones
Mike