Prices: 

California modification and testing start at $10,000 

1996 and up: 

Require OBD II

1967 model year vehicles and older:

No modifications and testing are required to register the vehicle in California.

1968 model year to 1974 model year vehicles:

Require compliance with USEPA requirements.

1975 model year vehicles to the present:

Require a "Certificate of Conformance" issued by the ARB (CARB)

Diesel vehicles:

1979 model year and older with original-equipment diesel engines are exempt from Direct Import lab testing requirements.