You are correct in some aspects but the gauges are very accurate at reading the voltage (all it is is a voltage meter. doesn't take alot of sophistication to produce an accurate one, just look at pocket testers). Problem is they dont read in fine enough detail. For example with the autometer you have the last led is at .1V, the next to last .95 the one before that .90 then .85 and so on. The first problem is as you will notice two-four leds are lit at one time at WOT. first you must determine which is brightest. say the brightest one is at the third led .90V. All you really know is its between .85 and .95V. In reality .86 is bordering on unsafely lean while .94 is pretty rich. Mine hovers between .90 and .95 led at WOT. All its telling me is I'm running a safe ratio but it cant really be used to tune for max performance without being able to read in finer detail than .05v. And the autometer has 20 leds total. Those meters with only 10 leds and so on are absolute junk. You have a little to work with at .05V. The gauges themselves are as accurate as your o2 sensor.
