I am gonna probably ask a dumb question here, but you did get wide band o2 sensors right? Anyways, Stoichometric Ratio is 14.7:1, that is what the manufacturer sets your ratio at for catalytic converter longevity. A little leaner, you get better fuel economy with a chance of detonation. A little richer you get better performance. Even richer if you have a turbo or supercharger. Generally, mid 13:1 to mid 14:1 is good.