Do you think NOS excellerates a need for a rebuild.Fact or Fiction.

 

If you run higher than normal RPMs it will ware out parts faster. If you use as much safety precautions as you can afford you should not have any problems. Think of it this way...if your looking into a nitrous system and you do get one, like I have, VERY soon after you will be wanting to make your car go faster. This will make you go through the motor anyway. You can burn valves and pistons if you run lean but a fuel pressure safety switch will help to avoid that.

 

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small to moderate shots - no. At least no more than any other power adders (turbo or supercharger). Larger shots (150+), well you're certainly more likely to run it too lean or wind up with too much cylinder pressure and blow a gasket or something.
In general as long as you take some time to understand what's going on and you don't do something stupid, you're motor will still live a long and happy life on the bottle.