That's why I said "behind" 6-7 psi. The fuel pressure in a carb is basically just an aid to keep it "primed" I guess when the signal pulls it out. The booster atomizes it. The difference is that EFI relies on fuel pressure to push it out of the injectors. I was also guessing at that so based on what I linked to below, my idea that it's more efficient to spray the fuel at higher pressure vs. pulling it out of the bowls may be incorrect.
That’s why there are different styles of boosters so you can control how well (or not depending on what you want to do) the fuel is atomize leaving the booster.
I don't know how annular vs. dog leg makes a difference as far as what the intake sees or perhaps how it performs once the fuel is suspended in the air. Does an annular style booster provide a better "shear"? We're kind of splitting hairs here but you know, just for kicks...
Thinking about that idea, I found an article written a little over 12 years ago. Retro fit EFI has come a LONG way since then so I take this article with a grain of salt. It does talk about the difference in atomization between the two systems.
Caburetors and Electronic Fuel Injection Systems
"The carb has a proven advantage over EFI in most applications according to Hilborn Fuel Injection’s Andrew Starr. “We have found that when comparing a common plenum carb to common plenum EFI, the carb typically makes more power,” Starr explains. “This is because the booster of the carb shears the fuel into fine droplets, allowing it to mix and stay suspended in the air column inside the manifold. This reduces the chance of the fuel droplet falling out of suspension and makes for a better burn in the combustion chamber. EFI on the other hand sprays the fuel under pressure, which is not easily picked up by the moving air stream. Coupled with all of the reversion pulses inside the standard common plenum intake, this promotes fuel separation, reducing combustion chamber efficiency.
"The only time we really see a marked increase in power with EFI over carburetion is with the use our individual runner manifold, which offers greater air speed over our common plenum along with the lack of reversion. This also allows combinations with cams that would be considered too large for normal street driving to have excellent low speed torque and excellent part throttle drivability. It is not uncommon for one of our injected engines to make 60+ rear wheel horsepower over a carburetor."
The article does mention reversion so maybe an anti-reversion plate is something worth investigating. Reading between the lines in the 2nd paragraph (disregarding the idea they're talking about individual runner manifolds) kind of confirms what I was saying that previously less-than-ideal situations can be made to work a little better on the street than with a carb.