Yeah, there are good cops out there... but this instance, I would be very angry too.
I have seen calvin's car a week ago, and it is basically stock bar a few bolt ons. I did not pick anything wrong with it and the cops comments were just unreasonable and unjustified.
You should not worry too much as you know what is right and wrong, but it is inconvenient to have to go through the process and deal with that kind of discrimination.
I am not sure where you plates are sitting, but from what I know as long as it's secured and visible it should'nt be an issue. Otherwise put the plates in the original position by bending the crap outta it so it will fit and ask them... "how do you like that now"?
Sorry for the long post.