EFI fuel pressure ?

[Denvervet]

I am planning on using one of Ricks new efi tanks that is set up for 58psi regulator. Brings up a good question. Why do aftermarket EFI system suggests 42-45psi vs some other pressure? What could or would be the downside of running more or less?
I will be running accel Gen 7 but that's just the ECM . I am not running their regulator or fuel pump, etc.
Is there a difference with how the injectors perform with pressure difference? I can imagine there is but....?