I know most states are 10 years or more behind California, back in the 80s and 90s here in California it was fairly easy to get a smog cert on a wink and an nod but it has been getting tougher. If you are lucky enough to get someone to overlook the visual, you might get buy with that if you tail pipe reads clean but shops are leary of loosing their license (cash cow) and if you fail once you go on the watch list and most likely will end up going to a state run certification center.
Also note that our Zs are supposed to be ULEV and ULEVII, so the standard at which they are tested will most likely be higher than the last car you owned.
Stillin is CARB approved for the Stage 2 only (SC with Intercooler)
APS is trying for CARB cert their TT system, this is what I am hopping for.
Vortech is in some kind of limbo and still not approved (I think they need to work on the piggy back box, ARB hates things with adjustments)
Dreamworks claims to be 50 state legal but has no product.
As for other states I have only this to say SAVE YOUR OEM PARTS. If your state decides they need another revenue stream by charging for smog certs, they could require your car to meet the standard at which it was sold. Here in CA it cost quite a few of us dearly when we had to dig up intake manifolds with EGR valves, cats, smog pumps, and stock carburetors.
Chris