Exhaust studs

My old exhaust studs looks good, but I have some new and was thinking replace them?
But I have not been able to get them loose, is there any tricks / clever way for removing them?

It`s maybe not critical to not replace them either?

If the threads are looking good don´t try to remove the studs, they can easily snap of.

i left mine alone ;;; y risk snapping those little bosses ;;