Just an update on this issue. It would appear that 812 is the number that makes the EPro happy. When it was programed at 1000 for speed cal when we ran a measured mile it said 1.23 distance traveled. When I changed it to 812 it said 1.01 on the same mile. The owner of the unit said it was reading 10 mph while he was following me and I was trying to keep the car as close to 10 as I could. Will know for sure in a few days when he gets back to spraying. 

Thanks for the ideas and suggestions.