I think you are looking at the Robart valve wrong. There is one air in. (the single center nipple) That gives you two up outputs (one for the nose gear and one that needs to be T eed for the mains) and two down outputs plumbed the same way…… As far as pressure, the line diameter, length of line, and restrictor setting will not change the pressure to the gear. It will only affect the length of time to get the pressure to the gear.