So your car passes emissions, but you can't drive it? What kind of car? Swaps ARE legal as long as they are done correctly. The engine must be the same year or newer than the car, have all correct USDM smog equipment in working order, pass visual and sniffer test, etc. You can have the car inspected by the california BAR, otherwise known as the smog referree. If it passes, you'll get a nice sticker saying what swap you have and that it is legal. A part being CARB certified means that it is certified to not adversely affect emissions and make the car a polluter. The testing is expensive however, which is why most cheap intake systems don't have carb #'s.