At WOT I would not go over 12.8 really for me 12.5 is SAFE but 13+ is way too lean IMO get it to 12.1-12.2 for added security the extra fuel will give you more torque on the top end and help with detonation or knock retard. 14.5-14.7 is what the truck will be looking for under normal throttle and at idle. Now for nitrous you need to be much richer at WOT but thats a whole different discussion