I've heard this argument being made, but I'm not sure I buy it. Motorcycles have horns and if a car is coming too close, they can honk as well, or move out of the way, just like cars and trucks do for each other, without having to be loud. Straight pipes, which have to be installed on the bikes in order to make them louder, are illegal in NYS, though when the bikers are given tickets, they just remove the straight pipes, appear in court with a document to that effect, the ticket is dismissed and they re-install them. Most of the motorcycle groups do not advocate installation of straight pipes and feel they only serve to promote "exhibitionist" behavior - revving of the bikes, lots of noise, drag racing. When I worked at the City Council, the head of the New York State Motorcycle organization came down on a few occasions to testify against straight pipes.