There is a difference with California legal and Federal legal emission systems. However if the Mazda Miata is equipped with the Federal (49-state legal) smog parts which it was originally equipped with, it can pass the California smog check and register with the CA DMV. If the Jeep Wrangler which you'll be bringing into California has not had its emissions system tampered, the check engine light is not illuminated and its emission monitors are "ready", the vehicle can pass the California smog check without any emissions system modification and/or upgrade.
