I've had my SHO higher than that, and honestly don't plan on doing it again for a long time haha. Makes you nervous running a 4400lb awd sedan where not many have gone before. Don't know where the weak link is at those speed and I certainly don't want to find out ha.
The SHO definitely pulls pretty good up top. It's not great, but there's a lot of drag. Going past the 140mph speedo does not take long!