my uncle ownes a smog shop in california and told me that he had a customer come in with hho installed in his car. he said it blew threw the test with flying colors but because it did not pass the visual inspection he could not pass the vehicle.. now aint that about a *****. guess the only way to "legaly" install hho on a vehicle in the states is to put it in a pre smog car... skip that im gonna do it anyways