This is a handy spreadsheet that can be used to estimate the horsepower potential of a set of injectors, as well as see how appropriately your pump(s) and injectors are sized to each other. 

Data is entered into the yellow cells, notes are on the bottom of the spreadsheet. 

Obviously voltage to your pump is a big variable in regard to pump flow.  The flow data shown here was not all collected at the same voltage, or on the same equipment, so keep in mind there are variables here. 

A car with a properly functioning electrical system will typically have 12.5-13 volts at the pump itself.   The only pump listed where flow is not affected by input voltage is the Injector Dynamics BPC100 (as of Nov 2019, not yet available for purchase).