As I understand it the in tank lift pump on a 2.7 TDV6 with the seimens CR system should produce 0.5 bar with the filter system you describe (although I have only seen this filter on the disco 4)the As Steve said easiest place to measure this is at the bleed screw on top of the engine.
I have found general rule of thumb is the 2.7 has a dipstick and the 3.0 has none.(for future information)
I hope this helps