Motorcycle noise is an economic externality. Person A gets 55 units of pleasure from his loud exhaust. 1000 other people get 1 unit of pleasure ruined by their loud exhaust.
therefore, teh total benefit to society for the loud exhaust is -945 pleasure.
This is always the case, it's an immutable law.
As for the loud trucks, since they serve a more meaningful purpose, they are not quite the economic losers.
Basically, if you ride with loud pipes, you are saying your small amount of pleasure is worth the massive amount of displeasure. And if everyone acted like this, well.....
Basically we have seen the only reasons people can justify loud pipes.
Reason 1: Fuck you, I am more important
Reason 2: It's not that big a deal, you're a pussy.