I think I remember reading something that said that a wideband O2 isn't very accurate if placed after a catalytic converter...that right?
So how would I go about getting some real a/f data for my Z on a dyno if it still has the stock manifolds and cats?
Is a trip to the dyno going to be worthless for tuning wot a/f ratio?

 

The wideband needs to be an inch or two from where the stock o2's are now for a good reading. Putting them after the cat will give you false readings as to what the PCM is seeing and any computer tuning will be inaccuate.

 

That's exactly what I remember reading. Thanks.

More questions though...
So a shop that has a wideband that they just stick in the tailpipe...that won't work on a car with a cat or cats. So how can I get a/f data for my Z?
Am I stuck buying a DIY kit or one of the new pre-fabbed kits and putting a bung in the stock y-pipe?

I remember when we dynoed my GN (which used to have a Random Tech 3" cat on it) they just stuck the wideband in the tailpipe and didn't worry about it. The a/f data seemed about what I would have expected as it was in the low 12's and the line was pretty flat.
So should I assume the info for the GN wasn't accurate?

 

I'm not really sure about the tail pipe probe vs the wideband o2 thing. I would think the tail probe would work and is designed for cars without cats. Maybe someone else could give a better answer.