Yea I didn't see that it only pushes 12psi when I seen it
just to add some reasoning...
HEUI engine's need to refill each injector
in between each and every injection event (as opposed to keeping an injection pump 'primed' like a conventional diesel with a
fuel injection pump)
at high rpm, there is verrrry little time to get the fuel
into each injector to refill it, before it is commanded to fire again.
in relative terms, a 7.3L (6.0L, etc) needs both high pressure and high volume from it's fuel pump...
the other makes/models with conventional injection pumps simply need to keep their injection pump's 'primed' with fuel, to prevent damage, to their internal plungers.
a 7.3L would run fine with 12psi...at idle...but as soon as the rpm came up, and presumable fuel delivery increased (with boost)...the 12psi wouldn't be enough pressure to refill the injector bodies with fuel.