As far as I understand it. The car has to be at the level of US import standards.
It must comply with emmissions and safety.
All these items need to have a US DOT number on them.
Ford wasissed an emmissions exemption for things like air pumps, etc, but you weren't.
Many states have statutes that exempt cars 25 model years from emmissions testing.
The GT5's are too new and are not exempt.
If you go to the PI website and look at the black GT5 for sale it will state that the car is not emmissions legal in CA.
Basically that is why.