GPZ1100 link pipe size

Hey all, does anyone know the size of the pipe after the 4 into 1 collector on a 1982 GPZ1100

Im making up my twin undertail yoshies but dont have any headers to size up the link pipe.

Thanks in advanc

It depends upon which brand of exhaust you have. Additionally, some brands have the midpipe attached to the collector, some have the midpipes attached to the muffler.