The valvebody is disassembled and cleaned and the shift valve bores are polished to keep the valves from sticking during operation. JET reprograms the shift points using its own recipe of modifications. New springs are used on the regulator, scheduling, and accumulator valves. Other springs on the cutback valve and the servo modulator valve are exchanged for plugs or balls. Finally, one passage on the separator plate is enlarged. What all this means is you get firmer, later, quicker shifting from your C6.