A brake system (10; 600; 800; 900; 1000; 1500; 1600; 1700; 1800) comprising: first and second wheel brakes (16a-d; 616a-d; 816a-d; 1028a-d; 1710, 1712, 1730, 1732; 1802, 1804, 1806, 1808); a reservoir (18; 613; 813; 1024); a brake pedal unit including a housing (24; 1030) and a pair of output pistons slidably disposed in the housing, the output pistons operable during a manual push-through mode such that the pair of output pistons are movable to generate brake actuating pressure at first and second outputs for actuating the first and second wheel brakes, respectively; and a plunger assembly (300; 500; 620; 700; 820; 1300) comprising: a housing (400; 502; 702) having first and second ports; a motor (422; 522; 722) driving an actuator; and a piston (410; 530; 622; 730; 822) connected to the actuator, the piston slidably mounted within the housing, wherein the piston pressurizes a first chamber (450; 590; 630; 790; 830; 1450) when the piston is moving in a first direction to provide fluid flow out of the first port, and wherein the piston pressurizes a second chamber (452; 592; 636; 792; 836; 910; 1452) when the piston is moving in a second direction opposite the first direction to provide fluid flow out of the second port, wherein the first and second ports are selectively in fluid communication with the first and second wheel brakes for actuating the first and second wheel brakes from pressurized fluid within the first and second chambers, wherein fluid may flow from the first and second wheel brakes into the first chamber (450; 590; 630; 790; 830; 1450) when the piston (410; 530; 622; 730; 822) moves in the second direction, and wherein fluid is permitted to flow into the second chamber (452; 592; 636; 792; 836; 910; 1452) via a first conduit as the piston (410; 530; 622; 730; 822) advances in the first direction when the first and second wheel brakes are actuated, wherein the first conduit is in fluid communication between the plunger assembly (300; 500; 620; 700; 820; 1300) and a boost conduit arranged between the second port and the first and second wheel brakes (16a-d; 616a-d; 816a-d; 1028a-d; 1710, 1712, 1730, 1732; 1802, 1804, 1806, 1808). first and second wheel brakes (16a-d; 616a-d; 816a-d; 1028a-d; 1710, 1712, 1730, 1732; 1802, 1804, 1806, 1808); a reservoir (18; 613; 813; 1024); a brake pedal unit including a housing (24; 1030) and a pair of output pistons slidably disposed in the housing, the output pistons operable during a manual push-through mode such that the pair of output pistons are movable to generate brake actuating pressure at first and second outputs for actuating the first and second wheel brakes, respectively; and a plunger assembly (300; 500; 620; 700; 820; 1300) comprising: a housing (400; 502; 702) having first and second ports; a motor (422; 522; 722) driving an actuator; and a piston (410; 530; 622; 730; 822) connected to the actuator, the piston slidably mounted within the housing, a housing (400; 502; 702) having first and second ports; a motor (422; 522; 722) driving an actuator; and a piston (410; 530; 622; 730; 822) connected to the actuator, the piston slidably mounted within the housing, wherein the piston pressurizes a first chamber (450; 590; 630; 790; 830; 1450) when the piston is moving in a first direction to provide fluid flow out of the first port, and wherein the piston pressurizes a second chamber (452; 592; 636; 792; 836; 910; 1452) when the piston is moving in a second direction opposite the first direction to provide fluid flow out of the second port, wherein the first and second ports are selectively in fluid communication with the first and second wheel brakes for actuating the first and second wheel brakes from pressurized fluid within the first and second chambers, wherein fluid may flow from the first and second wheel brakes into the first chamber (450; 590; 630; 790; 830; 1450) when the piston (410; 530; 622; 730; 822) moves in the second direction, and wherein fluid is permitted to flow into the second chamber (452; 592; 636; 792; 836; 910; 1452) via a first conduit as the piston (410; 530; 622; 730; 822) advances in the first direction when the first and second wheel brakes are actuated, wherein the first conduit is in fluid communication between the plunger assembly (300; 500; 620; 700; 820; 1300) and a boost conduit arranged between the second port and the first and second wheel brakes (16a-d; 616a-d; 816a-d; 1028a-d; 1710, 1712, 1730, 1732; 1802, 1804, 1806, 1808).