This is a great thread talking about a lot of the various pump options available and links to various tests showing the flow rate vs pressure:
According to SOS, if the Walbro HP 255lph is ~65% greater than OEM, then OEM is ~255/1.65=155lph.
Larger capacity pumps may require a more robust wiring mod and a different FPR. Extreme high flow setups will require those in addition to modified fuel rails and fittings, and a larger capacity fuel filter.
IMO, with the RDX injectors and a later CTSC, just a new OEM pump or Walbro along with a fresh OEM filter is sufficient.