No shittin, I was gonna ask the same question. Well anyways, a/f gauges really are riceboy toys and serve little purpose (from what everyone says). But, I have a dual pod with only a boost gauge and I can pick up a matchin a/f gauge dirt cheap. I'm also in the same boat as you. I need to know how to hook it up. I got this from mkiv.com and I think you hook it up to h5 some how. Can anyone help us?
When you get the A/F gauge (I recommend a 20 segment display such as Autometer has) you will see from the wiring diagram for the gauge that you simply connect one of the wires into the ECU harness. You don't need anything under the hood. Just get the pinout diagram for the ECU harness and use a vampire clip or solder job to connect to the O2 sensor. It's pretty easy. If you can't get the pinout, I have the Toyota wiring manual and engine manual if anyone needs something looked up.
Hey guys thanks alot! I am in the same situation that you are in LowerJerZey... I have a dual pod with only a boost gauge and I got this thing for a gift. I thought it might help out a little once I get my AFC installed but I just needed something to fill in the hole in the pod.