Natural gas pressure regulator having adjustable valve seat

A gas pressure regulator includes a body having respective inlet and outlet ports and an interior chamber defining a gas flow path. A hollow piston is moved in relation to a valve seat to create a junction through which gas is directed along the flow path to the outlet port. The piston engages a valve seat, thereby defining relative open and closed positions based on the position of the piston and the pressure of the gas, the piston being axially biased by a spring. The valve seat is attached to an adjustment member having at least one externally accessible feature to enable the axial position of the valve seat to be varied relative to the spring biased piston. In one version, the gas pressure regulator can include a heater assembly extending into the flow path adjacent the outlet port, enabling ported gas to be heated before introduction, e.g., into an engine.