well if you ever foot break a turbo car you know boost starts to build and continues till it starts pushing the car. With a two step it holds the rpms down so the brakes well hold the car. A two step will also instant spool the turbo since it sends unburnt gas into the turbine housing wich ignites there spooling the turbo faster (the popping sounds you here). I spray a small shoot of nitrous just off the line till 10 psi. It helps give some low end tourqe. Also even after it cuts off you still feel a deference from how much it has cooled the intake tract.
