I just read a very interesting post: “Best Kept Secret…”, on Racepics.net, by Frenchy, in the Bench Racing Section, on engine tuning using O2 sensors. Check it out.
NOTE: I called JEGS and the unit that is referenced in the post is no longer available (from JEGS). Everything is much more expensive now. All they carry is various components or kits by Innovate Motorsports, which would use the Bosch wideband O2 sensor(s) for giving A/F ratio.
I had O2 sensor bungs in both sides of my last set of headers, but never installed the sensors. I may put them in this set of headers.
Since I don’t plan to use Nitrous, I know I can use my years of experience at reading plugs to get by. For all the N2O people, you might consider the A/F monitoring system. Four hundred dollars is not too much compared to a head or a complete engine.