if it's only having issues when you launch at the track, i bet maybe you are getting a bunch of knock off the 2-step, and it's fudging up your whole run. When you do a log off a pull on the street, with no launch, you aren't dealing with the knock.

log a whole run at the track, from before burnout to past the finish

 

Dont take offense here but my friend was having the same problem as you and I told him two things. First he had terrible tires, his 2 step wasnt set up properly, and his driving was not the best either. Most of the time its the driving, all I can say is practice on your launching and shifting they make a big difference. Hope this helps.

 

Clean off the 2 step as knock count goes.