Question about RODI pressure in lower mainland

[chi]

hi everyone,

Got a general question about water pressure for the ro membrane. I recently attained a pressure gauge and installed it right before the ro membrane. With the waste water restriction to open, the pressure is tiny, around 10-15 psi. But if I close it to more trickle the pressure reads 40 psi.

My 4 way auto shut off was replaced just now and as well as the check valve.

Before my waste water just kept flowing....if i restrict the waste water flow, should the asov work better? Do I have to go out and get a booster pump?

Thanks!