ORIGINAL: jombo
if you want to go to a lower nitro content its just like breaking in the engine again, you need to do the procedure all over again.
When you change %s you do not have to re breakin. You will have to retune, but breakin is so the parts can go thru their heat cycles and wear in, once they are broken in, there is no need to do it again until you rebuild with new piston & sleeve.