I saw this vid
and like the sound and the look so I've been in touch with Baak. They suggested that their universal fit cans https://www.baakmotocyclettes.com/en/parts/262-universal-exhaust-muffler-slip-ons.html might do the job but I want any changes to be reversible. They have told me that they will be working on specific Bobber-fit parts soon so I'm holding on, fingers crossed.