Power Steering Flow Control Valve
From Detroit Speed & Engineering
This flow correction fitting will reduce flow from 3 gal/min to approximately 2 gal/min while retaining the appropriate pressure in the system. This flow correction fitting should be used when a GM power steering pump is used with a Mustang II rack and pinion.
Tech Tip: A power steering pump with a 3 gal/min flow rate can overboost a Ford rack and pinion. The steering will feel "twitchy" or "nervous" if our flow correction fitting is not used.