I did 150 mph on a flat road and into a crosswind and it was unpleasant. Without a windscreen and fairing, the turbulence made it no fun, and I was pretty much over it and forever satisfied.
Buuuut... just now on Christmas day I had a wide-open stretch going downhill (maybe 1-2%) and a perfect 10 mph tailwind. I got up to 150 fast and easy and held on until I saw 160. And it was much nicer than my previous time; the air turbulence was not nearly as bad. I guess that tailwind made all the difference. It felt like I had 20 more HP. It was a pretty awesome day.