There was a NOS'd lude back in the days of PUK. I'm sure some of the older members will remember Dave "Oldgit" with his nitrous'd 4th with nostril vent purges
Oh, and as for insurance with nitrous, just don't drive on the public road with it hooked up. Simple. Obviously you still have to tell insurance you have the pipework set up for NOS, but just no NOS being run.
Few of my buddies from the old drag racing days (and just to clarify, I'm talking proper drag racing) who ran NOS found the insurance problem. We had no problem insuring a couple of 70's Chevys with twin turbo V8, or one with a supercharged V8 from a Nascar, but you put some laughing gas in your car and it's a nightmare!! So we checked up on it, and as far as I'm aware (and I'm sure Shiny can confirm on this one), it is still the case that if you have the bottle in the trunk of the car, or somewhere away from where the connectors are, it's fine. Just when you want to race, just hook the bottle up, race, and then when done, put it away again. Insurance should be made aware though that you have the connectors but just let them know that there is never NOS connected on the public road and you should be fine.