AFR is simply your ratio of Air to Fuel NOT Fuel to Air. The number displayed on your wideband is the mass of Air to Fuel. 14.7 AFR means that the mass of air is 14.7 times the mass of fuel. Consequently the lower that number, the LESS air in the mixture which yields a rich AFR. And similarly, the higher that number is, the MORE air you have in the mixture which yields a lean mixture. As a rule of thumb, 14.7 (stoich AFR) is the optimum AFR while cruising so you're good to go there. When people say rich and lean, it is always in reference to a certain AFR.
As for full throttle, that number all depends on how much power/torque you want to squeeze out of it. 11.6 sounds fine tho. The richer you go, the safer it is and less power/torque you'll make. The leaner you go, the more power/torque you'll make. However, the leaner you go, the higher the chance you have of detonation. Again this is speaking in terms of full throttle.
When you say "headers breaking down" do you mean to say that your engine is winding down? If so, your wideband will go VERY lean, which is normal - mine does the same thing. Besides, the engine is not under any real load at that point
Overall, your AFR's look fine IMO
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