I have just bought 2002 z28 camaro with heads and cam, and i was looking for air fuel ratio gauge that work on the obd, so have any one bought A/F gauge that work on the obd?

 

Are you looking for a gauge that reads the stock O2's (aka STFT's) or an actual AFR gauge? If the latter, then I highly suggest just installing a WB O2 that is independent of the PCM. Also, if more mods are in your future, that is the route most take.