depends on the 044 pump, apparently there are two types. one which will hold 5BAR and peak at 6BAR and the other that peaks at 8BAR and will hold just over 6BAR.
part numbers are different, but the later are rarer IIRC.
they both flow about the same 200ltr/hr just one can run higher pressure.
8BAR would be handy if not wanting to change injectors e.g. i have siemens deka IV's and they run 630cc at 3BAR static, but can flow 900CC at 6BAR static.