I don't know how this system works exactly because my brother pointed the same thing that how can deposits be removed if you are putting it in a closed loop system. But i saw this in Imtiaz Super store for 730 rupees and thought why not give it a shot. After using it I noticed my car idling a lot more smooth and the little jerks I used to feel while accelerating disappeared. It was worth a try but I am not sure if it wil help rectify car problems. It feels more like a preventive method rather than some sort of mechanical cure. But never the less it worked fine for me. I read some good reviews about it too.
And it is for all engines, carbi or EFI. There is also another product called "STP Gas Treatment" but I don't know what will that do to my car and since mashAllah my car is trouble free, I don't need to try that out yet.!!