A valve assembly includes a housing, a flow controller, and a piston. The housing defines an inlet port, an outlet port, a flow path extending between the inlet port and the outlet port, and a pilot chamber configured to be in fluid communication with a pilot. The flow controller is positioned along the flow path. The piston is positioned to separate the pilot chamber from the flow path. The piston includes a first end in fluid communication with the pilot chamber and an opposing second end positioned to engage the flow controller with a pilot force that varies based on a pressure at the pilot.