From what i understand, some other tuning device could be hooked up to the FPR solenoid and you could select the CC of injector you're using to reduce the fuel pressure so all the values on the map would still run the car the same as before.
BUT! The SS AFC or FTC does not have this ability and you must reduce every value on the map to get the same fuel ratios with bigger injectors.
If you want you can get a fuel pressure regulator and manually control the fuel pressure yourself. But it's propbably easier just to select all in the SS software and decrease by percentage.