Right, been and done a bit more thorough testing with the multi meter, the gauge i have on the pump was reading a tad low to start with, proper readings are........

at idle speed........
13v @ alternator and engine bay power supply's
12.8v @ Battery in the boot
12.5v @ fuel pump

On fast idle, at a guess 2.5k
13.4v @ alternator and engine bay power supply
13.2v @ Battery in boot
13.1v @ fuel pump.

Stu, i know it never drops under full boost, always stays the same as it charges at, so about 13.0v

I still think i should be getting more?