Boost has nothing to do with oil pressure. Revs can change pressure. Your oil pump is mechanically driven, it is linked to the motor. So the more the motor revs, the more your oil pump spins, the greater the pressure. This is counterbalanced by the volume your pump can physically supply. It gets to a certain rev limit and no matter how hard it spins or increases revs, it physically cannot pump any more oil, it has reached its maximum flow rate. The maximum flow rate is also affected by the type of oil, the gallery and journal/bearing size, and the scavenge supply [if you flood the head and starve the bottom end supply].