[D1sclaimer]

Its the same thing as a NOS-05122 kit which is the kit I have. Zex is just in a fancy box. Im running a 70 shot dry.

For spark plugs. I would definately get rid of the oem platinums if you're spraying. The nitrous will eat away at the platinum. Go with copper or iridium. I'd do copper cause you need to check your plugs and read them way more frequently with nitrous to make sure you're running fine. If you're taking them out, you might as well throw some new ones in since copper plugs are very low cost.

I run NGK 7173 spark plugs gapped to .038. They're copper, resistorless, and 1 heat range colder than stock. For a 55, you don't need colder plugs, but if you want to spray more, you will. You can get them at advanced auto parts, o'rileys, and most other auto stores. You might have to order them though cause most places seem to be out of stock most of the time. If NGK 7173 plugs aren't cold enough for you, NGK 7405 are the same, but 2 heat ranges colder than stock.

As for how it works...

The box has almost everything in it. A solenoid, relay, and fuel pressure bypass. As soon as nitrous goes through the solenoid, the fuel pressure bypass takes a little bit of the nitrous and makes your vehicle think you need to run as much fuel through the fuel system as it can. In other words, it used the fuel pressure regulator to run alot of fuel through the fuel system. The fuel return line puts most of the fuel back into the tank. This is a safety measure so you don't run lean. Nitrous is sprayed into the intake and you stay in a safe air/fuel ratio from increasing fuel pressure.

Theres more to it, but I think thats what you were asking for.