I deliberately didn't use exhaust paste when re-assembling this joint. After wire brushing flares, donut and inner part of clamp I used copper grease which remains effective to over 1000°C. The parts are free to settle into a gas tight position when tightened up, with less strain on clamp. Joint will also come apart easier later.
I used copper paste every time I worked in bike exhaust parts - that means a thousand Times.
It saved me hundred of hours when working again on the exhaust!
