I too would be concerned if mine was that loud.Here's a couple of sound bites of my 1999 Curvy with 22K on the engine.
First one with original exhaust and second one with the Chinaprovich Slip-on I fitted,
https://app.box.com/file/179198067326
https://app.box.com/file/218563217522
I run Smith and Allen Motorcycle oil and add some Mso2 Moly to my oil.