I've only had nitrous on one car, a 1991 Lotus Elan. I had it custom installed at a speed shop. It was a wet system with a NOS nozzle installed into each cylinder's intake tract just like your fuel-injectors are. He bent the tubing to run BOTH fuel and nitrous to each nozzle. Afterwards he "jetted" each nozzle so that the combination of nitrous & fuel was stoichiometric (neither rich nor lean). I had a WOT switch so the system only armed when I floored the gas pedal. There was also an RPM window-switch so it only armed within a certain RPM range. I used it for years. The only problem I ever had was that the bottle-heater didn't automatically switch off one time and it got so hot that the emergency pressure-release "cap" (just like a freeze-plug on an engine-block) blew and I had a very long & noisy nitrous release into my trunk. As I was in Florida I never reinstalled a bottle-heater again! The guy who installed it said that a multi-port nitrous system like that was the most reliable way to go.

P.S. Make sure someone REALLY CLOSE TO YOU can refill your bottle(s) with nitrous, as driving across town to get refills was the biggest pain in the ***. The farther you have to drive will determine how many bottles you want to have. Swapping the bottle out is super-simple.