the narrow band disco light O2 sensor gauge is junk. they can be somewhat calibrated....but the refresh rate on them is so slow you cannot see true readings.....and the readings you do see cannot be trusted.....the greddy guage I hear is pretty good as asubstitute....it uses its own wideband O2 (you install abung from what I gather....and I like typing bung cuz its funny)....


You are better of with an exhaust gas temp gauge.....it will let you know when you are going lean easier than those air fuel meters....