[MATCHBX]

The way you might want to approach this is to tell him that it's not so much the fact that they can't flow enough fuel because of their size, but because the fuel pumps have such bad volumetric efficiencies at higher pressures that you need to start out with a larger flow to be able to have the needed flow at the higher pressures.

If you look at the link from RRE you will have definitive proof of why, in an engine that needs higher fuel pressures, you need to upgrade the pump. Not higher boost pressures so much, but the higher FUEL PRESSURES needed. Any fluid pump is going to get less efficient as the pressure demands on them go up. The chart that's posted on the RRE site just goes to show what kind of horsesh!# efficiencies these pumps have across the board. The Walbro's come in at 50% at 12.5volts and about 70% at 14volts for efficiencies. The OEM ones are even worse.

I think that's the biggest reason for upgrading. They are capable of flowing all kinds of flow at low pressures, but it's the higher fuel pressures that make them not able to keep up.