1. It's N2O
2. Both kits are similar. I know someone is going to come on here claiming that NX is better, because they rate their kits at the wheels. In actuality all they do is use bigger jets and claim they make more horsepower. Both kits are expensive and have similar features. If you are new to nitrous, start out at the 70-75 shot level. You'll need one heat range colder than stock NGK copper plugs, gapped to .030" for nitrous use, and you'll need to retard your ignition timing a few degrees. Use it responsibly. Don't spray below 3000 rpms, and don't hit your rev limiter. Don't make consecutive runs on the nitrous back to back, and don't spray for more than 15 secs at a time. In the future if you want to go above the 75 shot level, you'll need an inline fuel pump and aftermarket ignition. I would also recommend some sort of progressive nitrous controller, like the jacobs nitrous mastermind. Just remember, tuning is the key. Bad tuning and being irresponsible in its use will lead to blown motors.