The timing is increased whenever the smc reduces the MAP voltage from what it should be, which is basically always. The SMC reduces the MAP voltage so that the ecu thinks that there is less load on the engine than there really is. The ecu then decreases the duty cycle of the injectors and increases timing to run more efficiently and increase power. The problem is that the larger the injectors you run with an afc or an smc, the more that the MAP voltage is decreased in order to compensate for the higher flowing injectors at the same fuel pressure. Thus, the more timing advance you will see under closed loop boosted conditions. Honestly, I would feel safer running a decent regulator on stock injectors boosting 8 psi than I ever would with an afc or an smc and larger injectors. This is simply because reducing the MAP signal in our cars is a flat out bad idea unless you are na.