Emission upgrade components you can use in California must come with an Executive Order (EO) number. This number will indicate the component(s) is approved for use in California and will not harm emissions.
Many high performance emission components will be advertised for sale in California but not for use in California. Insure anything you purchase (especially on-line) comes with a California EO number; the number should be stamped on the unit.
posted by SmogTips Support
