Im not sure if you can splice into your exhidting O2 sensors or if you would need to add anothe O2 sensor for it to work. But then since you have EFI and O2 sensors doesnt it automatically calibrate? I always thought they were a tool to help adjust n tune carbs.
If you want just a simple Auto Meter gauge, that can be spliced right into your stock o2 wire off the computer. The only thing with the auto meter a/f ratio gauge is that its not accurate and the lights tend to bounce all over the place. It would be helpful in a very extreme lean or rich condition though.
A wideband a/f monitor on the other hand will tell you your instantaneous a/f ratio. Most have a digital readout that is very easy to understand. They come with a new wideband o2 sensor that replaces for factory one, and most come with a narrowband output that tricks the computer into thinking the stock o2 sensor is still there. The only issue with them is that they cost $300+. If your stang is pretty much stocka wideband isn't a must, however, it is good to have one if you plan to heavily mod in the future.
Anything other than one of the $300+ wideband A/F setups is pretty much just a light show like Christmas tree lights.
The computer has a limited range that it can adjust the A/F ratio automatically. Turn up the fuel pressure enough and you can override the factory settings. However, the best way is by using one of the portable computer tuners like the Tweecer. Then you can set the A/F ratio according to the needs of your particular engine setup.
If you still want the "Light Show" here's some tips...
Use 43 (Dark Blue/Lt Geen wire) or pin 29 (Dark Green/Pink wire ) on the computer. Use Wire tap-ins from Radio shack P/N 64-3052. The computer is located under the passenger side kick panel. That keeps you from having to crawl under the car and make a weather proof splice in the wiring. You can use either one, or run a SPDT switch and use both. Then you can use the switch to select which side to view.
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)
The A/F gauges that use the O2 sensor signal will jump all over the place. The reason is that the O2 sensors "switch" between .2 volt lean and .6 volt rich with a curve that looks like the drop off a high cliff. The curve is almost straight up and down, so the voltage shoots from .2 to .6 and back down . again 2 or more times a second at cruse. You won't get much useful information except when the mixture is extremely lean or extremely rich, there is no middle ground.
I wish my autometer bounced around... it just hovers around the lean section... Unless you plan on spending the money for a wide band, buy another gauge. It's not that pretty to look at and its not even backlit.
Keivn
I had one before. They work with the stock sensor if thats what your asking but as someone else said, they are just eye candy unless you get a wideband setup
Wideband is the only way to go if you want it for tuning purposes. The autometer and cyberdyne gauges are only useful for filling a hole in a gauge pod.