I'm not using a box, but I might as well be. I use a blinder and cover up the first 2 bulbs on the tree. I just sit staring at the last buld and as soon as I see a flash I let the transbrake go. you have to play with front tire pressure, 2 step rpm, and the button if it is adjustable. once you figure it out it is pretty easy to repeat RT's within a small window.
thats a whole other thread, lol!
I run in the Modified class. its the same thing as Super or Footbrake. we are allowed to run anything except a delay box.
I'm running super stock springs with the fronts clamped up tight. QA1 adjustable shocks all around, and slant 6 torsion bars.