I looked down the first couple miles and it had me at a low 7 pace, a little while later i saw 11.
There were clocks on the course every mile, and i knew i started 34 minutes after the first wave,
so i was able to do math for most of the race. I was also running with the 3:50 group for a good long time.
Went through the half way point right on time.
check the Strava track - doesn't follow the streets very well.