Your 2003 Toyota Camry should not have a problem passing a California smog check and being registered in this State without needing any emission system modification.
It's true, there is a difference with California legal and Federal legal emission requirements. And, for the most part California is stricter. However, a USED vehicle, such as your 2003 Toyota Camry, if equipped with all the Federal required emission components it came shipped with from the factory, can pass the California smog inspection process and be legally registered in this state; as long as your Toyota's exhaust emissions fall within California's limits.
A 2003 Toyota Camry being relatively new car, we assume it should not have a problem passing the smog check in California.
