flow resistances add more like electrical resistors in series where pressure is analogous to voltage and flow to current. Therefore reducing the resistance of any one element results in increased flow of the entire system. This is easily checked against our real world experience because we know that upgrading intakes and intercooler piping show real gains even if the throttle body remains at 50mm. By the same logic, a throttle upgrade should show gains although naturally they'd be bigger when paired with any of the breather mods.
