In theory, more piston area equals more force applied to the pads and discs.
"The hydraulic force ratio is determined by the relative area of the master cylinder bore and the total piston area of the calipers operated by that mastercylinder.
We adjust the hydraulic force ratio by varying either the size of the caliper piston or the bore of the master cylinder. The amount of fluid displacement is directly proportional to the bore size. Therefore a larger cylinder will require more foot pressure per unit of hydraulic pressure generated but will require less pedal travel to exert the same amount of force."
Steve