My old Zetec Focus made 83hp and 128ft/lb's extra with nitrous. With proper tuning and precautions it won't harm anything more than any other power adder. Interesting how people popped motors on the pathetically weak jackson supercharger but, I didn't on nitrous. I put most of the miles my car had with spray and was getting a bottle at least every other week in the summer months.
You have things like: pressure gauges, bottle heaters, rpm window switches, fuel pressure safety cutoff switches, progressive control etc to make it even safer.
The main reason nitrous gets such a bad name is that people just buy the cheapest of the shelf kit and use the jet chart without dyno tuning. Also people think "oh that was fast, this jetting will be even faster!" and you know what happens
next.
The things they are doing with ECU control nitrous setups are amazing compared to the old days. They can use spray to make up for any turbo lag and tapper it off seamlessly as boost comes on. My only regret with that car is that I put so many bottles into it I could have bought a great turbo setup.