Many forms of forced induction can pass with proper tuning. Sometimes you CAN get away with no cat and great tuning, but a high flow cat is recommended for ease.
Although I think the PLP Powerdyne unit would be the easiest kit out there to pass emissions.
Call Mike @ PLP, ask him directly. He knows tons of info regarding SMOG testing in Cali. And if he can get a kit to pass there, the eastern seaboard should pretty much be covered :wink: .
PFS, Toyomoto, TBKO and srt are among other tuners to pass emissions using turbo kits of various stages. The main issue is getting an Air fuel ratio that produces the least harmful emissions, then going home once you pass and load up your badass, high power profile and fuck the Ozone over! hahaha j/k...
Call up various tuners and ask them about there emissions testing, and what they've tried and where they've passed to get a better idea.
Kane