RTV in place plus Muskrat's lock wire on the problematic rings, surely things will stay put now. I've never had to use silicone or lockwire on an exhaust. The other bikes here& previous all used threaded connectors and gasket rings of some type to make the in head connection. If tightened when hot, they work well.The header to silencer connections just clamp up tight to seal. The dry connection make for easy removal/ replacement.
Won't be having that ease of removal with this BSA and its glued in exhaust, so hopefully there won't be a need for exhaust removal anytime soon!
Glen