Here is a thread that I wrote at another site that should help you out a bit. The comments are meant as a guide and not intended to be law:
http://www.mustangtuningforums.com/s...hlight=nitrous
Also, this info below might help too:
Use this scale below for help. I am assuming bottle pressure is at 950 1000 psi for the examples below:
50 shot: Stock timing is fine and stock plugs are ok too
75 shot: May want to retard timing one degree using a chip or tuner. One step colder plugs are a good idea too especially in the summer.
100 shot: Timing should be retarded one degree and definately use one step colder plugs gapped at 0.35. Stock fuel system is fine still at this point
125 shot: Max safe point for stock fuel system. Definately one step colder plugs and timing retarded one degree. May even have to retard timing two degrees at this point (based on detonation).
150 shot: Requires upgraded fuel system (pump or pump and injectors). Might get away with stock fuel pump and pressure regulator. Two degree of timing should be backed out and two step colder plugs are probably needed. Not considered safe by some to the bottom end of motor.
175 shot: Start to think about upgrading the bottom end of the motor. Two to three degrees of timing should be backed out and two step or even three step colder plugs needed. Definate fuel system upgrades. Not considered safe by most to the bottom end of motor.