I don't think it would pass California's smog test, but I don't see why it wouldn't pass emissions. Set it at a low boost setting equal to stock: Less air=less fuel=less emission. If you are scared and want to actually spend some money, (random thought) get a custom midsection made with a highflow cat and put it on the day of emissions for a total of two cats.

But really, as long as you can control your boost, it shouldn't really matter at a low setting. Just an idea. Don't quote me on it.