All KRC power steering pumps provide the racer the ability to fine tune the feel and assist in the power steering system. Interchanging the -6 outlet fitting can alter the steering input the drive has. The more flow your steering system receives the easier it will be to turn the wheels, but will decrease feel. Having less flow will put feel and stability back in the steering system, but decrease assist. Each optional flow valves has an I. D. stamped onto it to help you identify the flow valve easier. Flow characteristics are listed on the chart below. They can even be changed quickly without removing the steering pump from the car. KRC changeable flow valves are only compatible with KRC steering pumps. Larger flow valves are required when using steering quickners or 3. 4 inch per revolution or faster rack-and-pinions. If you run on smaller tracks, a larger flow valve can give you more assist through the tight corners. Cars with wide tires and a lot of positive caster may also require more fluid flow. If you drive into the corner and feel as though the steering has a slight catch to it, commonly called "pump catch", a larger flow valve may be required. Smaller flow valves can be used on tracks with long straightaways or long sweeping corners. By decreasing the flow you can gain more feel and stability in the steering system. Also those running Mustang style racks, you may require a smaller flow valve. The most commonly used is ID: 6. Selecting the Proper Flow Valve: When selecting a flow valve for a race track only car, the driver should use the valve the feels the best at race speeds.Pit Stop USA offers KRC -6 Aluminum Flow Control Valve - 1.58 GPM - ID=6 25306000 at low everyday prices. Be sure to check out all of our products from KRC Power Steering including KRC Power Steering Flow Control Valves.