Putting the bike back together after some new valve shims, it appears I have a bit of stretch in the timing chain. The punch mark on the 'I' side of the intake cam aligns perfectly with the top of the cylinder, but i have a choice of half a tooth above or below the cylinder for the punch mark on the 'E' side of the exhaust cam. (All valve train components are stock) Would one be preferred over the other (slightly advance or retard the exhaust cam)? I've done a search, but haven't found the specific answer. Much thanks!