The race cars with turbos... run 18:1 afr at cruise with lower than gas egt.. on stock timing.
I have tested wot afr from 10.5 to 13.5 with very little power difference inbetween. Not to say there are situations where you would want rich or lean setups but for the "I wanna run e85 and a smaller pulley" guy its going to work fine.
So you ignore the injector offsets and just adjust other fueling to sustain your Afr then?
06 GXP | 222/227 cam/cartuning turbo kit on 8psi/meth/e85 coilovers/ still on stock trans at 130k