A flow restrictor for use on a pilot operated relief valve (PORV) assembly with a pilot valve that regulates operation of a main valve to reduce pressure in a system or vessel. In one embodiment, the flow restrictor is configured with a plurality of flow modifying regions, namely, a first region and a second region that is spaced apart from the first region. These regions are configured to generate flow at the outlet of the flow restrictor that induces operation of the pilot valve that is favorable for operation of the main valve. In one example, the first region and the second region define, respectively, a first flow area and a second flow area for the flow pathway, wherein each are configured to assign a ratio of the second flow area to the first flow area with a value of less than 10.