If you want to cool the intercooler, but not increase the cylinder pressure substantially, then CO2 is a better option to spary onto the surface of your intercooler.
If you want to make more power, and already have a pretty good safety margin, you are better off sprying the nitrous closer to teh intake manifld - after the intercooler.
If you want to create a safety net, use a methanol systme like the AEM, Snow, etc.