ga289stocker:
No cats result in high hydrocarbon emissions and this is what the sniffer is seeing. If the engine is running a little rich then the HC emissions will be high-ish. If the engine is running a little lean, things should be better. There are "guaranteed to pass" chemicals that you can put in the gas tank and they might help. Regular fuel (vs. 93 octane) will help, too. Sorry but I am not smart enough to know if you *need* cats to pass the sniffer test. My guess is that it will be quite difficult without cats.
As an alternate to swapping out the intermediate pipe for the stocker, you could put in some high-flow cats (Magnaflow, CatCo, etc.) but that option is not inexpensive. You won't notice a decrease in performance, just a bit quieter tone and a less "gassy" smell in the garage. Even with high flow cats, it is common to have the rear O2 sensors turned off in the tune. An alternate to adjusting the tune is to install MIL (MIL = malfunction indicator light, or, check engine light) eliminators on the rear O2 pigtails.
Last thing I can suggest is to run a search here. I'm sure somebody with an off-road pipe has gone through emissions testing.
HTH,
Chris