Fight it! if you sure he couldn't have clock you at 80mph. Don't tell anything about the overspeed before to the judge. Just say you didn't go that fast. The chance is he won't even show up to the court. But if he did, he will use what ever you said after he pulled you over to against you. So, next time you get pull over, don't say anything like I am sorry or stuff like that unless you feel that he will let you off it. Goodluck.