all it is for is under a load it takes extra pressure from the front and boosts the rear to compensate for the load.
there is not a return line like shown above all lines are pressure just used at different times (when needed)
and just plugging off will work just will have a low pedal. (that is how i did mine bu i am using chevy 4x4 calipers in the rear and they need more volume and pressure anyways)
