[hogcowboy]

I agree they are probably custom. About the only thing that is similar but round are Cobra's. Following are bike specific however.

Cobra Speedster Long Exhaust For Yamaha Road Star 1700 2008-2013 - Cycle Gear

Cobra's Speedster Long exhaust system combines traditional shotgun styling and modern performance technology. These triple-chromed, shotgun-styled pip…

www.cyclegear.com

I think I'd give them a call because they do make odd mufflers with similar shape.