The ZEX system is a good first N2O system. However, I found it didn't give me enough control or protection. It's only control is the WOT switch. I preferred a little more protection so I bypassed the ZEX electronics and integrated an FJO Racing 2 stage nitrous controller. With it, I can deliver the nitrous based on RPM or time and even lock out first gear. I also used the second stage to control a shift light.
Check it out here: http://www.allfordmustangs.com/forums/showthread.php?t=51678
Check it out here: http://www.allfordmustangs.com/forums/showthread.php?t=51678