Dyno Vs.Drag Strip Testing

A buddy of mine attends quite a few flash-light drags around here, they are close and cheap to participate in, but no times.
Closest drag strip is 3 hrs away
There is a local guy that set up a chassis dyno in his garage, he charges $40 for three pulls.
After the first pull, the first thing he said, "Your converter is wrong, you are driving thru it"
He still made 420 HP at the rear wheels, but immediately changed the converter, and it made a huge difference in how the car drove.
Sounds to me as if that guy is worth more than $40 for three pulls.