Not dumb questions at all I miss stated in saying volume the correct variable the surface area or diameter of the working pistons of the cylinders involved. In most duel master cylinders the port to the rear or nearest the input rod end will have the smallest working area. This is do to the first piston in line having rod in the middle of its working surface to push the second. The diameter of this rod is subtracted from the area of the first piston. This port will most likely be for your front brakes as they will most likely have the least surface area in wheel cylinder piston working area.
