160 in a Carrera GT on the back straight at Road A
150-160 in a few GT3's

Now for my own car, 130-140 (typically 136mph w/o traffic) but i've probably done it 800-2000 times, I has no idea

It is true though, I just have no desire to go flat out on the street unless the moment/area/car that's running away from me is just perfect. Also, I typically let off after turn 9 at Road Atlanta just because those extra mph's is more like a waste of brake pad now instead of the rush I use to get just getting everything out of the car at every second (unless I am running with people)