Abstract: A valve is disclosed for regulating the flow of a pressurized working fluid through a nozzle having a nozzle throat. In a preferred embodiment of the invention, the valve comprises a valve body defining a valve bore, a pressure inlet and a nozzle plenum. The nozzle plenum fluidly communicates with the nozzle throat. A valve seat is disposed between the pressure inlet and the nozzle plenum. A valve member is slidably disposed within the valve bore. The valve member comprises a first end disposed proximal the valve seat and a second end distal the valve seat. The first end comprises a valve face and the second end comprises first and second rear surfaces. The second rear surface is spaced apart from the first rear surface. The first rear surface cooperates with the valve bore to define a rear chamber. The second rear surface cooperates with the valve bore to define an actuation chamber, the volume of which is not a function of the valve member diameter.