you dont have to sell the A/F guage, but If you want it to be accurate and useful, go and pick up a PLX M-250($250) and a PLX M-Series AutoMeter Narrowband to Wideband Gauge Converter($35) and make your A/F guage as accurate as any windband guage... I have 1 and it works perfect!!!, well I have the converter. I run the PLX M-300 WB. and tune with the M-300 and am waiting on my new R-500(using for all my tuning jobs), PS this thing moniters EGT,Knock,Boost, and even has a Dyno, with a G-meter *Option)....Thank you SANTA!!!