i had the zex kit, real easy to install and stuff...but i dunnno. now i love nitrous express...they are the best in my opinion, a little harder to install though but a 55shot zex was weak compared to the 50 shot NX. www.afterhourzracing.com has the best prices ive ever seen for nitrous express, but they cant list the prices on their site because NX *****es at them for selling so low...but anways for a price quote, you can email them sales@afterhourzracing.com . to use nitrous, you should ALWAYS be at WOT and most kits have protection built in so that it cant engage when you are not. you should also be above 3000rpm , and usually dont wanna spray in 1st gear because you will def just burn right through your tires. good luck.