Factors and conversions don't matter. As far as NHRA is concerned 10.00 = 6.40, Their 8.50 number is 5.35 for the 25.x, and 7.50 is 4.50.
The rule book is vague (as in it's not there) except for the 9.99/6.39 numbers needing the basic cert. Also they have MPH numbers of 135+ for a basic cert and 180+ for 25.x. Sounds like the 1/8 mile stuff they leave up to the tracks to a degree.
If the results don't match the theory, change the theory.
