Difference between both systems is that NOS and NX use basic selenoids so when you press the button it shoots no matter if the pressure is high...and the zex kit comes with a computer that wont allow it to shoot nitrous if the pressure is too high. I have had both and i prefer ZEX anyday. I am selling my upgraded zex kit if anyone is interested. I just bought a venom kit, which in my opinion is the best kit in the market but also two and a half times more expensive. But if anyone is interested the zex kit i have contains 2 bottles, 2 bottle warmers, purge kit, nitrous guage, bottle link for 2 bottles, all the steel lines and the zex computer. This kit cost me over $1000.00 but I am not expecting that much so make me offers. I will consider them.