Has anyone installed an air/fuel ratio meter on their Z? If so, could you please provide some instructions or a how-to? I'm asking about a meter (shows lean or rich), not a controller.

 

The Greddy one is the best one I've seen that is still reasonably priced. Simply weld the O2 bung on the manifold or downpipe and insert the O2. Works well and you can calibrate it against a wideband later on with the adjustment screw.