Duc,
Yes they pulse the solenoids. Some pulse only the NOS, the new ones pulse both. They are easy to tune, but do not have gear dependant ramps, only time based. Schnitz's new controller is the smallest, and also has the ability to set "dual" stage ramps.
I have developed a circuit to activate after the 1-2 shift on airshifted bikes. This allows the spray to start in 2nd gear, no worry about it in first.
Dave