Maybe the following links will help you understand nitrous a little better:
"Intro" to Nitrous Nitrous Oxide and Pistons - Technical Before installing nitrous oxide on my Cougar, I did a ton of research and actually bought a great book ... the title escapes me now ... I will look it up when I get home. Anyway, one thing I learned is that nitrous increases cylinder pressure just as a supercharger or turbo would, but with some special side effects.
Because cylinder pressure is increased, spark timing is critical! Too soon and you could be dealing with failed head gaskets and rings, or even runaway detonation if you nitrous/fuel mix isn't just perfect or slightly rich. Too late and your exhaust temps go through the roof and you end up burning valves and frying exhaust components.
However, when nitrous brakes down into it's nitrogen and oxygen atoms are released, we now have two nitrogen atoms, that tend to stay together (N2), which act as a buffer to detonation. So, if the timing is exactly perfect, higher compression can be run safely.
Due to the exactness that is required though, I would agree with the assessment in the second link ... better off running regular compression and putting all your efforts into getting as much nitrous in the engine and make sure that it is properly mixed with enough fuel.
