totally, that's another factor of course and talking pressure differential of one side of the injector to another.
say we're on no boost, then you can run injectors at 3BAR (43.5psi), then say we chuck in 20psi of boost, then the differential across the injector must still be 43.5psi, so we need to get 63.5psi of fuel pressure into the injector to compensate the pressure change.
Then say we chuck 30psi of boost into the mix, then we'd need 73.5psi of fuel pressure to keep the same differential to keep fuelling linear, which a rising rate fuel pressure reg should do.
the problem is making sure the fuel pump can cope at this level, hence the need for uprating them.
i noticed a big difference when going from an rsturbo pump to my 979 pump, flows a lot more and handles higher pressure better, i actually pulled ve values out of my table when i did this. my next pump would be the 413 (IIRC) 044 type pump or a walbro 255 one if i have any fuelling issues again up the revs/boost.