How fast can NJ police go without lights on?

This is in reference to another question which you can find here -a href="http://answers.yahoo.com/question/index?qid=20101130162659AAhlmQR&r=w"http://answers.yahoo.com/question/index?…/a regarding some tickets I recently got. As I was speeding the state trooper was speeding with me, and when we got up to a certain speed he decided to turn his lights on and pull me over. Essentially he was pacing me to about 70mph (perhaps a little higher), making it seem as if he were racing with me, then he turned his lights on. I'm quite sure this is wrong as far as pulling me over goes. How fast can a State Trooper go before turning his lights on? Shouldn't he have turned them on when we both began to exceed 55mph?