Can a supercharger pulley terminate a warranty, and is there any way that a 15% pulley will damage the Supercharger or engine?

 

Yes and yes. There's is a possibility that a pulley will damage your supercharger and if that happens the waranty will not cover it. It's very rare though, there's thousands of cars with pulleys and only one or two failures that I know of and I think they were all 19%+ pulleys. I've had my 16% on for 8,000 miles without a problem.

As far as waranty goes, if an aftermarket item causes a failure there's no way they'll cover it. But, if the failure wasn't due to an aftermarket item they have to honor the waranty. They'll likely blame it on anything aftermarket you have if at all possible.