Progressive controlled is the same as a nitrous kit explained above but used with a progressive controller. A progressive controller can be fitted to almost any nitrous oxide system providing that the solenoids are constructed in such a way that they are able to pulse. When we say pulse we mean that the solenoids are continuously turned on and off in a pulsing manner which fires a small amount of nitrou sat a time. Good progressive controllers allow you to program the progression of which it lets nitrous flow through the solenoids. A typical setup would allow you to start with using a small amount on nitrous and then ending up with a constant flow or longer burst of nitrous as the rpm rises. Progressive controllers are used so that nitrous can be safely injected into the cars engine to create extra power from the start line. Without the progressive controller you can only fire nitrous oxide into the engine when the throttle is wide open and revs are high. When the system is activated and the car takes off, small amounts of nitrous will be pulsed into the engine and larger amounts as the rpm rises.