Of course there is always a risk of detonation, that is why for every 50 hp of nitrous it is reccommended you retard ignition timing 1-2 degrees. If you run just a 50-75hp shot - you can usually use premium gasoline (93 or greater octane) to solve this for you. The few horsepower lost in retarding the timing these few degrees is well renumerated with the extra power being added.
...As for nitrous being dangerous on a ZETEC, yes it is if it is mis-installed or used incorrectly. I have quite the experience with this. The ZETEC 16V motor can use a properly installed DRY N.O.S. nitrous kit jetted for 50 hp.
...As long as the kit is installed properly, jetted sensibly!!, you use PREMIUM 93 or better octane gas and your fuel pump is in good working order(check fuel pressure) there is no reason for the ZETEC to fail when using nitrous.
...Nitrous should only be used for a MAXIMUM of 15 seconds at a time. These motors are not very sensitive to nitrous - just very sensitive to being misused. Give a gun to a kid without showing him how to PROPERLY use it safely and your asking for trouble. Same idea applies to nitrous use with the Zetec.
