Well, being as I'm not from California I don't know what exactly will or will not pass.

The A'PEXi website doesn't mention anything about CARB exemptions so I couldn't tell ya one way or the other on that one. My guess is that even if the bolt-on versions are exempt, the 2.5" collector version is not because it is designed for a car that was not sold in this country, that being the JDM 98spec ITR.

I'm guessing that if you have a JDM ITR 4-1 with all of the heat shields in place for the header and catalytic converter then you won't raise any eyebrows such that they would even look for a CARB sticker. If you're looking for a place to get the heat shields this is one possibility although I'm sure it's available elsewhere. Technically this setup is not legal but you should pass the sniffer test and not have any CEL codes, so who cares about a technicality? If you're trying to be stealthy I'd probably go this route.

Oh and about the Kteller exhaust: I would suggest the 2.5" stainless bolt-up piping kit with an 18" resonator, and either the 2.5" turbo-style or 2.5" dual tip muffler. They can also probably weld you up a Carsound cat with the proper flanges and oxygen sensor bungs, although they don't have it listed on their site.