Hi, I personally run good times in the 400. I am 8th grade and haven't lost a race, always getting first in my area with a PR of 57.50. Searching google I have found that that exact time is called "A good time for a 13 year old." But that is ridiculous. The time your son got is amazing. I say that time is what last heat runners will get. Depending on other runners times he should de exceedingly well in a meet.