u trick the ecu with the AFC. if the hks is pretty much the same as the apexi, what it does is it takes the amount of air the mas sensor is sending back to the ecu and converts to what ever amount u want it to. So to lower the amount of air the ecu sees going into the engine, u would just lower the amount with the afc. and that also lowers the fuel, because less air = less fuel. And the ecu wont give u fuel cut if it doesnt see a reason to.