Actually, no matter how low the boost you add, you WILL get some advantage.
All normally aspirated engines operate under a vaccuum condition in the intake manifold.
All normally aspirated enginrs have a point at which "volumetric efficiency" becomes nil. Simply said, they can't suck in enough air, so as to overcome the inertia of the air itself, that they start to choke. Choke is actually a bad word, as the engine cannot drag enough air past the venturis, in a carbureted engine, to drag fuel in. So they lean out, instead, to the point that they die.
If you can boost the air by "even" 2 psi, you will raise the max at which the engine starves, again.
At 5000 RPM that 350 needs 500 CFM. When your manifold vaccuum rises too much, you are sucking less than the engine needs to burn the fuel. To add an electric centrifugal blower that can PASS over 500 CFM, not only as boost, WOULD boost volumetric efficiency, as would be demonstrated by those naysayers here who have had their intakes polished to reduce resistance to flow, such as Extrude Hone's process.
And, 9 in a row, is an exagerration. A centrifugal compressor, a blower in this case, doubles the pressure, per stage..
I'll have to get a measurement from some of the blowers in the garage. I know you can't hold your hand over the outlet, at least not easily.
I've built them, in a factory, large ones, that were capable of 10,000 PSI, and that is not a misprint. These were centrifugal compressors, for deepwell oil applications. Some damned dense air, when you got to the last few stages. No piston, nor gear,nor vane pump could handle the volume required.
Cheers,
George
And the blower, as such, should not have that big a current draw. Work it out on your shopvac.ANY free air you get is a bonus.