[Extended Power]

On the bench, if you hook up a regulated supply to the bottom port, as soon as the valve lifts, I hear air passing through the valve guide. (Clearance of course.)
If I am using a boost controller, would I not plug the bottom port, as the control is done through the top port only. (Solenoid energized to keep gate closed, another solenoid to bleed pressure off the top, opening the gate...nothing on bottom port at all.)

Leaving it open just allows the soot to pass through the bottom port, an just gets everything dirty.