Can you explain the appeal of exceptionally loud motorcycles?

Spring is here, and along with it comes birds singing, bees buzzing, and (at least around here) motorcycles thwaaARRPPpping as they drive by.

I don’t mean the existence of motorcycles. Some are quite remarkable machines. Gorgeous to look at, fun to ride.

I’m talking about those custom pipes, usually on a Harley Davidson, that someone adds to their bike. Deafening loud and distracting.

Do you know what their intended function is? Do they serve a purpose I am missing?

Please enlighten me.