This is similar to the phenomenon going on right now (especially in California) with attaching whistles to the exhaust pipes of cars... highly annoying. As if the farting coffee-can exhaust tips weren't bad enough...

It's funny (not ha-ha funny) the amount of stuff people get away with when it comes to their automobile or motorcycle. Aircraft operations are governed by noise abatement rules such that many airports close down at specific times of night yet anyone can go blasting through that same area on a Harley equipped with noise-enhancing tailpipes or a whistler attached to their exhaust.