A fluid flow control device, comprising: a supply port for receiving a supply of pressurized fluid; an output port for delivering a supply of pressurized fluid; an exhaust vent for venting a supply of pressurized fluid; a trim cartridge disposed between the supply port and the output port and between the output port and the exhaust vent, the trim cartridge defining a cartridge supply port and an upper planar surface, the cartridge supply port being disposed along a supply path extending between the supply port and the output port, the upper planar surface disposed along an exhaust path extending between the output port and the exhaust vent; a spring cap defining a control signal port; a body defining the supply port and the output port; a diaphragm assembly disposed between the output port and the exhaust vent, the diaphragm assembly defining an exhaust port along the exhaust path and comprising an instrument diaphragm, a feedback diaphragm, and a perforated spacer disposed between the instrument and feedback diaphragms, the feedback diaphragm in communication with the output port of the body and the instrument diaphragm in communication with the control signal port of the spring cap; a diaphragm housing disposed between the feedback diaphragm and the instrument diaphragm and defining the exhaust vent; a control element movably disposed in the trim cartridge, the control element including a supply plug, an exhaust plug, and a stem extending between the supply and exhaust plugs, the supply plug in selective engagement with the cartridge supply port of the trim cartridge, thereby closing the supply path, the exhaust plug in selective engagement with the exhaust port of the diaphragm assembly, thereby closing the exhaust path, the exhaust plug comprising a lower planar surface disposed at an interface between the exhaust plug and the stem, the fluid flow control device characterized in that the lower planar surface of the exhaust plug is coplanar with the upper planar surface of the trim cartridge upon assembly when the control element and the diaphragm assembly occupy a quiescent position; and in that the diaphragm housing defines a cavity between the feedback diaphragm and the instrument diaphragm, the cavity having a first cross-sectional dimension adjacent to the instrument diaphragm and a second cross-sectional dimension adjacent the feedback diaphragm, wherein the second cross-sectional dimension is greater than the first cross-sectional dimension. a supply port for receiving a supply of pressurized fluid; an output port for delivering a supply of pressurized fluid; an exhaust vent for venting a supply of pressurized fluid; a trim cartridge disposed between the supply port and the output port and between the output port and the exhaust vent, the trim cartridge defining a cartridge supply port and an upper planar surface, the cartridge supply port being disposed along a supply path extending between the supply port and the output port, the upper planar surface disposed along an exhaust path extending between the output port and the exhaust vent; a spring cap defining a control signal port; a body defining the supply port and the output port; a diaphragm assembly disposed between the output port and the exhaust vent, the diaphragm assembly defining an exhaust port along the exhaust path and comprising an instrument diaphragm, a feedback diaphragm, and a perforated spacer disposed between the instrument and feedback diaphragms, the feedback diaphragm in communication with the output port of the body and the instrument diaphragm in communication with the control signal port of the spring cap; a diaphragm housing disposed between the feedback diaphragm and the instrument diaphragm and defining the exhaust vent; a control element movably disposed in the trim cartridge, the control element including a supply plug, an exhaust plug, and a stem extending between the supply and exhaust plugs, the supply plug in selective engagement with the cartridge supply port of the trim cartridge, thereby closing the supply path, the exhaust plug in selective engagement with the exhaust port of the diaphragm assembly, thereby closing the exhaust path, the exhaust plug comprising a lower planar surface disposed at an interface between the exhaust plug and the stem, the fluid flow control device characterized in that the lower planar surface of the exhaust plug is coplanar with the upper planar surface of the trim cartridge upon assembly when the control element and the diaphragm assembly occupy a quiescent position; and in that the diaphragm housing defines a cavity between the feedback diaphragm and the instrument diaphragm, the cavity having a first cross-sectional dimension adjacent to the instrument diaphragm and a second cross-sectional dimension adjacent the feedback diaphragm, wherein the second cross-sectional dimension is greater than the first cross-sectional dimension.