I've put the standard reg back on. The drive to work this morning was better, wasn't able to physically see the fuel gauge dropping as I drove, whcih is a definite improvement. I didn't get to the ecu mixture screw as I haven't touched it previously, and I'm hoping that when I get it on emmission test again later, binning the FuckingShitEquipment valve will bring me back into engine friendly figures again. All being well, an oil and filter change this evening should see me relaxed again, which is great.