I have two motorcycles, a BMW R1200GS with an Akrapovic slip-on exhaust which sounds fantastic but isn't particularly loud. It came with the bike new from BMW so I think that is the reason. The second bike I have is a fire breathing KTM 300 two-stroke enduro which not only sounds loud but also probably pollutes like like a truck. If I ride it directly from my house I sometimes just freewheel the first 50-100 m down the hill before I start it. It's a bit embarrassing and I wish it would be a bit quieter. I'm looking into a FMF pipe that is quieter.