Good description of this
I'm a Mechanic for a company that deals with custom built cars etc and the first time I seen this system I scratched my head and walked away lol. It is exactly like you explain, just confirming for those that say "NO YOU'RE WRONG FAST & FURIOUS IS RIGHT" LMAO.
For the more mechanically minded you have 5 systems. Dry, Wet Single Port, Wet Direct Port, Plenum or Propane & CNG
Wet Single Port Nitrous kit uses a system that sprays the Nitrous Oxide between the throttle body and the intake manifold where it Soakes Manifold with both fuel & Nitrous and the air flowing through the intake manifold and when it meets with the fuel creates a Higher power gain than a Dry system but does not come easy to fit if used professionaly. You can get kits for you're every day which is pretty easy to install
Wet Direct Port Nitrous Kit uses a system that pretty much does as it says. It sprays the Nitrous into each intake port of the engine. This means the intake stays dry & also the amount of Nitrous being delivered to each port can be change and not just have a constant flow like the single port system!. This system provides the highest power band of them all and also the most complex to install! Oh and lets not forget the price
Dry Nitrous systems rely on Nitrous gas being pushed through the Mass Air Flow Sensor which then tells the ECU (Electronic Control Unit) that there is a denser colder air flowing and that the Injectors MUST feed more fuel through the engine creating more power

. The length of time and and quantity of Nitrous gas obvious determines you're amount of power gain
Plenum bar Nitrous Systems are pretty much just an upgrade that you can add to the Wet Direct port System! This increases it to Stage 2/3/4 and so on but tends to lose power!
Propane or CNG System is basically just changing you're normal fuel and swapping it with a gas such as Propane which will rapidly increase power as you have a more stable Air/Fuel Mixture
