173 mph - 2003 ZX-6R
Redline was higher, but I ran out of balls/stupidity. At those speeds, when the thought of dropping your bike or hitting a moose start playing through your head, it brings you into check VERY fast.
It is not uncommon for me to go ripping up the interstate over 150... but it never lasts more than a mile before I start thinking about all that shit. Then the "fun" 150 and climbing becomes a "scared shitless" 150 and slowing down.