there's no safe way to run n20 without tuning. you have to be serious about it.

buy a knockbox and tune it.
nitrous loves high comp so you should be good.

while tuning the a/f is important, the only thing that actually destroys engines is predotonation and knocking.
IF you buy a knock box you will be able to monitor the engine during tuning and know exactly how far you would like to advance/retard timing, and how much fuel to add to ensure a safe tune.

its not all about power, its about RELIABLE power. i could throw a 100 shot on my car today and make 350-400hp untuned but for how long?