City psi is really variable. During the day 60 ish for example but at night when no one is using water it can go to 150 psi easy. Night is usually when pipes burst. Not really a lack of psi there. With out knowing city water psi. The only way you can really dial it in is with a combination of the restrictor, built in psi gauge, pressure switch, and pump bypass. 60 city psi on outflow is going to add to whatever psi the pump is set at 60 again as an example. It would be 120, hits the by pass and is now 110. At 110 psi flow rate also goes down to maybe 1L/min. Would need to look at the datasheet of pump to be sure. Should be a model number right on it. Do you have a pressure switch? If so what does it shut off at. Both pump and switch can be adjusted with an allen wrench. Doing all that would mean you could use whatever sediment filter you wanted. It doesn't change much anyway for the smaller microns. Would just have to dial it in for best membrane rejection. For those membranes your looking for 80 to 100 psi across them. 110 psi wont blow your membrane but might have leaky connections and lower flow. Can't really say for sure on my end what output psi will be with out knowing city water psi or pump model. It is adjustable though.
