Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.
Yeah I have the same shiftkit as Tim, I find I have it off for most daily driving as it can be a bit too harsh in daily traffic but when I want to play a bit it is cool for more solid shifts.
I will be able to give you back to back comparisons of any improvements over the 1/4 mile in the coming weeks as I have a suspicision my take offs are slower with the shiftkit on as the box doesn't allow the motor to flash into the boost revs at takeoff.
As mine is getting a full built stage III box in shortly I would be happy to send the shiftkit to anyone who wants to try it on their 4L60E.