fuel regulator

[Luke-saxo]

car started off as a 1.4 then had a vtr engine fitted today i have fitted a rallyie inlet and got the idle spot on a mate said now to swap the regulator to a 3.5 or a 4.0 what difference would this make i am not too clued up on the fuel side of things

anyhelp asap would be very gratefull

thanks alot

[AXracing]

The higher pressure reg would on a standard car make the car initially run a bit rich until the ECU rains the fueling back. It would also make it run rich under full throttle. Do you have any other modification that would require the higher pressure regulator?