I don't look at my speedometer intently, but I'd say maybe 115-120 mph max.
As far as passing everyone, I usually ride in Advanced group (groups are Advanced, Intermediate, and Novice), and I signed up for Intermediate group that day, since I had never been on that track before and didn't want to hold anyone up in advanced group. I started out about 10 seconds per lap slower than A group, but by day's end I was turning lap times that were a tick behind most of the A group. Of course most of those guys ride that track several times a year and know it inside and out, so I didn't figure I'd be at the front.