Can you get a section made up with aftermarket cats for the emission test? Then once you pass, put the stock exhaust back on and keep the other section for the next time you require emission testing? That way you can keep the factory exhaust and still pass the emissions test. Just unbolt and swap when you need it.
I guess I'm more concerned about the way the car is running - fumes, backfiring - and thought it was a direct result of the lack of cats. Also, what about the impact on the turbos with the altered back pressure? Arent' they engineered for a specific back pressure situation that includes cats?
I don't know....I've never heard of anyone with a turbo on their car wanting more back pressure. Most of the time you want a more free flowing exhaust. If anything I'd be concerned about overboosting after removing the cats.
I guess I missed your other post. Your cats are already gutted? Did you start having these issues after the cats were gutted? I'd guess the issue is more likely related to a bad MAF or something.