One day, with a tailwind so strong it actually knocked over a bike in the pits, I was able to see 182 (indicated) on an R1. It was still climbing, albeit veeeery slowly. This was at Spokane Raceway, the straight is probably near a mile long. At the same track on another day i wasn't even able to see 170 on a newer 2002 R1. I'm sure the wind was what made most of the difference though, since the windspeed was far more than the difference in the speed of the 2 bikes.
The day i tried the 2002 R1 there was also a guy there an a GSXR1000, granted he was a better rider and coming onto the straight with slightly more speed than me, he smoked me down the straight, put at least a second on me just there, maybe 2.
I've also ridden an RC51 and Mille R at that track but i don't remember the exact top speeds i saw, i believe they were somewhere around high 160's to low 170's, not too much faster than my R6.