A 2 step is nothing but a switch to allow you to use 2 different rpm limits. It plugs into your msd box where the rev limit chip normally plugs and has 2 places to plug chips into. There is a ground wire and a 12v wire that you hook to your transbrake switch from the 2 step. when power is applied to the 12v wire it switches to the lower limit chip. when power is off it switches to the high limit chip. The low limit chip is your launch rpm and the high limit is to prevent over-revving the engine. A 3 step works the same way but it gives you an extra limit chip that you use for the burnout.