Each County can make its own rules and Davis County is tough. One of the higher ups at the DCI worked for my father years ago and is also a friend. I went and sat down with him in his office to talk about engine swaps. This was a year ago and he told me that it had to be from the same manufacturer AND be an option for that year to be an acceptable engine swap. I argued that it would be more fuel efficient and cleaner but it was a no go. He didnt make the rules, just enforced them.
I believe that the State Law has presidence if you wanted to push it that far, the boys at Novak can shed some light here. My FIL lives in Washington so if I do it, I will register my jeep there and not even have to worry about it. Seems dumb to me if you can make it run as clean or cleaner than stock plus increase the MPG and still not be allowed to do the swap.
