Actually its just the assistance for the steering..

Im using a Toyota MR2 Mk2 power steering pump, as there wasnt any room for the original pump with the turbo..

I made a controller ages ago which regulates the speed of the pump, and allows you to change the amount of assistance you have..

In "Auto" mode, it will decrease the weight of the steering as the car slows down. It will also increase the assistance if the steering is turned quickly.. It will also turn the steering pump right down if the car is sat still with the steering still for a while..