If you're using a wideband probe that can do AFR, then about 15-16:1 at idle should pass an MOT, without being too lean. 15:1 worked out at about 2.5% CO on my scirocco.
John im using Tank, pump, lines and filter from a mk3 16v no mk2 pumps at all, cheers Mike im sure the motec can do both so ill check that out