If you have a good rotating assembly, the only thing else to worry about is supply it with fuel, and keep the timing where it should be. 4 degrees retarded for every 100 horse you spray is a safe starting point.
Do not ASSUME the fuel supply is ok. Make sure, it is. Nitrous wants something to burn. If not fuel, it will be pistons. Lean is bad.
Remember the old saying, pay me now or pay me later? With other "hop up" methods you spend the money up front. With nitrous, you spend it every time you fill the bottle. There is no free lunch.