I had to install 10 spacer washers to give adequate clearance, my silencer mount is on the outside of the footpeg mount, I've added some pictures so you can see how my silencer and secondaries are mounted, I measured my clearance at 20 mm. Hope this helps you out.
4 wheels move the body, but 2 wheels move the soul.
1982 Honda CB750 BOL D'OR
2017 Kawasaki GTR 1400
2017 Suzuki GSX S1000