FiTech EFI system

fishy68 said

Because at wide open throttle the air velocity is so great that even with a carb the fuel is atomized very well.

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One disadvantage w/ a carb is that it uses the venturi effect to suck in and atomize the fuel so requires a pressure difference to operate, thus a small throat to get that. With a properly designed venturi, much of the pressure is recovered so you can approach atmospheric pressure in the intake at WOT. With EFI, the throttle body throat can be much larger and doesn't need to form a venturi, so in theory you could get almost atmospheric pressure at WOT. A vacuum gage would tell you the exact loss for both.

Of course, if you install a super or turbo-charger, you make whatever manifold pressure your engine can handle (albeit higher combustion heat). That brute-force overcomes all carb venturi and intake valve limitations. Slant racers have shown how well that works on a head that flows poorly when relying on sucking atmospheric air.