The N2MB 2-step works by tapping into an ignition coil signal wire, brake switch, TPS, power and ground. You then set your "2-step" (soft rev limiter) RPM to the desired number and TPS input. You can also use outputs from this box as a nitrous window switch, shift light, and WOT box. I have my 2-step set at 2500 rpms....anything higher and I over power the rear brakes and push the front tires across the beams.