you can keep it street legal as long as the motor is the same year or newer and is USDM motor and ECU with emission equipment from the doner car. most fail because it's a hack job or OBD2 motor with OBD1 ECU or JDM motor once the swap is installed you make a appointment at a refree station they will inspect the swap and ok it with a BAR label. so if you get stopped they see it's a legal swap and smog shops will go by BAR label for inspection.