|Retard timing to 12 or 13, stock cats, no leaks and you should be good.
It's the visual inspection that is a nightmare. Trust me on this - once they "flag" you for something (literally anything but stock that doesn't have a carb sticker), the next inspector is obligated to check for the same faults. Part of the problem lays in the fact that the state doesn't just hold the smog shop accountable, but the inspection technician themselves. Meaning - no one will pass something that has already been flagged as their career depends on it, not to mention a huge fine if they are caught passing known failures.
I can't tell you how many times I've had the arguments about how my downpipes won't affect how clean my car runs, or how I need to pay my state money for a special sticker that tells them my air filter is an air filter. If the goal was clean air, why would any other test other than a sniffer and smoke test matter?
These problems are not going away in CA. They want to make it so difficult that people will give up driving their "dirty" cars.
Something else to note - the smog operation varies greatly depending on region. From what I have seen, I have it the worst here in the capitol. Give a performance shop a call and see if they can help.