A reading score of 170 on the MAP is the 99% percentile for kindergarten. It is roughly 82.5% percentile for 1st grade, and 34.5 percentile for 2nd grade. Those are the fall scores. For Spring, 170 is 90th percentile for kindergarten, 40-42 percentil for 1st grade, and 12% for second grade. So, if EJ has a score of 170 BEFORE starting kindergarten, than EJ is above the 99th percentile and reading like an average first grader half way through the year.
Hope this info helps!

Wisdom begins with wonder. – Socrates