Pocket bike exhaust. Sounds great, just like a little dirt bike. I love holding it wide open on a side street then grabbing the clutch to stop at the stop sign to hear my bike make the classic ping pinp pop pop pop sound as the rpms drop.
Very easy to do and doesnt cost much just keep in mind if you do this you will need to make your bike richer.
no need to weld I just used 3/4" copper tubing to make the header and springs to keep it all tight. After a few rides it will gum up inside of the copper to seal it up good.