Okay, here's the safe way to run a 75hp wet shot: (most of this a little overboard though)
-93+ octane gas
-2 degrees of timing retard (many claim that they didn't have to do this)
-colder heat range plugs (maybe)
SIMPLE! IT GETS NO MORE COMPLICATING THAN THAT! But if excessively lean conditions occur, you may want to invest in high flow fuel pumps and injectors and a fuel regulator and things like that.
*It is also important to know that most manufacturers design kits that will get the most horsepower using the stock fuel system and sometimes the stock timing curve.
*And believe it or not, I have enough lifelong knoweledge of nitrous that I really do not need to buy a kit from a manufacturer, because I can easily make my own. The most important rule to follow though when using nitrous, is to use it wisely, and to know what the heck you are doing.
I know alot about nitrous, but I have never used it on a civic hatch with an LS motor.