Did the 170+MPH run in my 2000 vette twice now. I thought the damn windows were going to blow out. It was so loud! Definitely a big difference between 150 and 170. Have done 150 quite often (10+) times, but 170 is a bit scary.
Wouldn't recommend it at any other time than at sunrise on a Sunday morning on a major freeway. Any slight corner or rise or dip in the road at 170 feels like you are 4-wheeling.