The safety of a nitrous system depends a lot more on periferals than the kit itself. I know basically nothing about using it on a bike but in a car you should add a fuel pressure safety which turns off the system should pressure fall, A window switch so it only comes on at safe rpms, if you activate it too soon the cyclinder pressures can get much too high, a WOT swtich so it only activates at WOT. An aftermarket ignition to limit rpms by cutting spark, many fuel injected cars have rev limiters that shut off the fuel pump which would be instantly fatal to the engine if the juice is flowing. You will need a colder sparkplug to avoid detonation.
Pay attention to all the safeties and most engines can take a fair amount of spray cheap out and skip parts and have one little problem with fuel delivery or something and things can go very wrong very fast.
I have been looking into it for one of my cars, do lots of reading before installing anything and you should be able to use it safely and effectively. In my application a V8 car most people and companies consider something like 125-150 to be the max without upgrading the bottomend but they guys who cross all the "T"s and dot all the "I"s have run as much as twice that with upgraded heads and cam to support the flow, but only because they did a thorough job of making sure everything was in place.
Last time I was at the dragstrip there was a hiabusa(sp?) which comes stock with nitrous and doesn't need it to mop up most other crotch rockets, I wouldn't have the nerve to crack the bottle on a bike but if you do let us know how much fun it is and how much that smile hurts after a few hours. If I go through with this it will be in a 4500pound car and only go 12s.
