I'm not sure the answer to your specific question but just thought i'd let you know that a narrowband AIR/FUEL (not FUEL/AIR

) really won't give you any useful info cause its only really able to toell if your rich or lean wrt stoichiometric. If you wanna do any type of tuning with a piggyback or something you should really get yourself a wideband AFR guage and o2 sensor, wouldn't wanna see you blow their motor.