Obviously being majority middle distance and long distance runners here, I think most of us would have un-official sprint PRs?
When my 200m PR was 24.2, I ran 2x200m and 2x150m in a training session in 24.2, 23.8, 18.0, 18.1.
How much faster is a 100m final leg or a 4x100m relay than a real 100m? I was clocked via video camera timer as doing 11.0 or just under 11seconds for the final leg of my relay once, assuming my starts are of average distance runner quality (ie. Not the best).... what do you think I could run in a 100m?