if you get pulled over by a cop and they look under your hood and they find an engine thats not supposed to be there or non CARB legal parts they can send you to the state ref.
you have to go to a california referee station, i know there is one in modesto and one in sac, probably more down your way too. what you do is call the BAR and set up an appointment and go to the station of your choice.
when you get there they will do three tests: visual, comprehensive, and emissions is what they are called i think
VISUAL: the referee will look over the car making sure all wires are loomed, nothings frayed, broken, jerry-rigged etc. and that all the parts/sensors that are required are there.
COMPREHENSIVE: this is where the ref will go over your engine/exhaust system with a fine tooth comb. hell check, cross check, and re check every number on your engine/tranny and make sure all parts for that engine are being used and so on. this is the hard part to pass. EVERYTHING has to be perfect, like right from the factory perfect.
EMISSIONS: pretty self explanatory, just your basic smog check.
if you pass all 3 tests theyll give you a plate that goes in the drivers side door jamb stating that the engine in that car is ok for THAT car. i beleive if you ever change the engine again youll have to get reffed again.
some people go to the ref because they are required to, some go because they want to run a jdm motor or a hybrid motor and not get in trouble. for example, someone will take a b16a2 and get it reffed in a 2000 ex then go home and swap a b18c/b16b or something a long those lines and be good because a cop wont know the difference, unless theyre honda savvy. others will go and ref an LS and then go home and put a b16 head for LSVTEC and be good to go because a cop will see "B18b" on the ref plate and see "B18b" on the block and assume its the same engine.
got it? lol