I’ve got a 2015 fz 07 with a Yoshimura r77 exhaust. My can is pretty damaged and I would like to get a new slip on. But my van is stuck in my bike pretty good, I’ll be able to get it off but would prefer not to until I have a replacement slip on in hand. Does anyone know what size the header pipe would be so I can order a new slip on to match that size 

I didn't want or need to disassemble mine but it looks to be 55mm (measured with a caliper). If I were looking for a slip-on, I'd pull the bad cannister and measure the pipe to be sure.