digital sol

I have a greddy a/f guage. I know its useless to have unless your looking at it when your on wot 100% throttle. When im on it all the way "wot" what should the guage be reading? The guage starts at 8 at the top and goes to 16 "in red". When i slam the gas it usually goes to 12 and works it way to the top of the guage "10-8". I dony know how to read the guage and it didnt come with instructions, wanna make sure im not hella lean or hella rich.