two step is for launching consistently
as mentioned read the instructions for hookup , the old dip switch boxes used ground of the two step wire to engage , the newer dial boxes need 12v supplied to the two step wire (makes hooking in to an electric trans brake much easier)
the two step will hold the rpms from going beyond what you set so you can just put your foot to the floor and when car starts going bup bup bup as it cuts ignition to random plugs you know you are at your target rpm ... set your rpm , get staged , engage the two step stomp the gas pedal and wait for bup bup bup ,when your'e ready let her rip
most use it with a trans brake and have the two step activated with the trans brake control so that when Tbrake is on two step is activated,
on a stageright tbrake you need to add a leaf switch at the shifter so switch will be closed when in low1 when tbrake is engaged , once you shift out off the brake the two step is disengaged ... hold on
it can also be hooked to your brake pedal along with a momentary switch on wheel to activate, run through wheel switch to a switch at the brake pedal (disengage with pedal up ), just hold the button at the wheel step on brake pedal , step on gas pedal wait for bup bup bup let off the brake and hold on , and sometime after you leave you can let off the wheel button