[art leong]

I've got my 2 step (launch control) working fairly well (I think?). It holds the rpms from about 3300 to 2800 against the footbrake.
My problem is the car surges (creeps) a little bit (3 inches in 5 seconds) when on the button against the brakes.
When I try to lower the rpms it just widens the surging.
My converter flashes to 5100 and it is a hard hit converter made to be used with a transbrake.
I can work on the 2 step a bit more with timing retard, or pull some fuel out.But I don't know how it will act when I let go of the button.
I've never used a 2 step before. Is the surging normal? It the rpm range normal? Will putting in a soft hit converter help?
This testing has been done in my driveway with no heat to the brakes. So can I expect it to hold a little better arfter a burnout?