yea, Rotarys shouldn't have Nitrous at all. And about the turbos, it depends on the car, a lot of times you get a number of PSI that the manufacture suggests as the maximum. Like on MX-6 GTs, it's 8.7 PSI, and if you go past it for some reason(if the turbo diaphram cracks, you will be going past that all the time), Mazda put an alarm and fuel cut off to prevent damage. I've been in a 626 5-door GT when the turbo was screwed up, and the alarm and cut off system didn't work, and it was fast as hell(in 2nd at about 3K RPM, the tires would light up and it was a rocket), but I'm sure some major damage was going on(didn't matter, the car was junkyard material to begin with).
You just have to go by the manufacture's specs...