Just tell the trooper your speedo was reading the correct speed limit. All he can give you would be a ticket for defective vehicle, no matter your speed unless it's REALLY excessive of the posted limit (like 15+).

Whenever you do get pulled over, DO NOT say how fast your were going. It's their job to prove your actual speed and you can make it worse if you say a number higher than they caught you at. That's why the first thing they ask you is "Do you know how fast you were going?" It's not about safety, it's about station revenue.

I drive as fast as I feel I'm safe. If the speed limit is 55 and people are passing me doing 80, I'm going to be doing 80 as well.

It also helps to keep an eye out for trap cars, learn their trap techniques, know what "unmarked" cars they use, and where they frequently hide.