Bosch C1 injection, Four new injectors fitted and coded,High pressure pump tested with Delphi and makes 1200 bar. Car starts fine and quickly and will drive ok up to 3000 rpm.

Looking at live data I have the following:

1000 rpm:
Desired rail pressure: 250 bar
Acctual 275 bar
Fuel Pressure Reg 18%

2000 rpm:

Desired 530 bar
Acctual 520 bar
Reg 28%

3000 rpm
Desired 620 bar
Acctual 490 bar
Reg 79%

I have checked the low pressure pump and it makes 2.1 bar connected directly to the gauge, connected to the pipe between the filter and high pressure pump using a T piece it only makes .3 bar, I am not sure which is the correct way round to check the pressure.
I have checked the O ring on the regulator and it looks good, I would like to replace it but apparantly it is not avalable as a seperate item, new regulator required ar £230. A new fuel filter element has been fitted, no sign of debris.
I can`t find any info regarding fuel flow from the low pressure pump in litres permin or hour etc
Also the higher the regulator percentage, the harder it is trying to increase the rail pressure, or is it the other way round? Using the delphi blank in place of the regulator gives the same rail preeure on cranking as with the regulator fitted.
Any suggestions would be much appreciated, Any more info, Please ask, Thanks Neil.