The conventional RNC (Restricted Nitrous Class) systems are the first choice for professional racers that are limited by jet size. These systems feature a CNC billet nitrous plate with enlarged nitrous passages, a .375" orifice Lightning nitrous solenoid, 8an feed line and a .500 orifice Lightning 500 bottle valve. The combination of these components results in a very dense liquid nitrous charge which allows the maximum amount of nitrous flow through a certain size jet. Results of these RNC systems are so impressive that you will have to use one to believe it.? Nitrous Express RNC (restricted class nitrous) systems are guaranteed to make the most power per jet size of any system on the market. If you don't make the most horsepower or are not 100% satisfied, NX will gladly refund you 100%.