[Hammer]

bolt ons will probably not void any warranty.

By law, a dealership cannot refuse work unless they can prove a certain modification was the cause of a failure, but at many dealerships, getting them to work under such guidelines require a lawyer and court costs. Not worth it in my opinion...

Also, if a dealership found out someone was by-passing the rev limiter and a failure occurred, you can bet your behind that they're not going to fix it under warranty.

As far as the term "power adder".....
in most cases it is forms of forced induction such as blowers, turbos, or nitrous oxide. It is usually not used in reference to normal bolt-ons such as throttle bodies....