Hello,
A "boost-a-pump" increases the flow, the pressure has to rise at least 1:1 vs. Meaning if base pressure is 12, at 10 lbs boost the fuel pressure needs to be 22 to maintain the flow. Any boost will push push back on the injector, reducing flow...hence the need for boost compensating regulator. If hooked to a vacuum/boost port, the pressure will reduce when in vacuum and VE table will have to be adjusted. Otherwise you can use a one way check valve just for boost, it will need a small "leak" so it doesn't work in vacuum.