I have 2 cars with 40 mm sidedraughts one mechanical and one electric. No difference.
However I would suggest spending $50 on getting a pressure regulator (passive inline one after the pump) and set it to 1.5 psi.
That is plenty of pressure for carbs and does not affect flow/volume.
Oh the only difference is that with them both being race cars, they can sit for a week or two after an event and the electric one takes one maybe 2 tries to start wheras the mechanical pump car takes maybe 8 starts before its able to fill the carbs and get the car to start. It also has low voltage points as well which could contribute to that.