Originally Posted by jsaps
With a piggyback like the JB4 the DME only sees factory boost levels, so nothing incriminating can be recorded. Other than vehicle speed.
So basically with a JB setup the only way they can actually have a leg to stand on in voiding a warranty is your top speeds? Is that a valid conclusion to void a warranty?[/quote]
A dealer can deny coverage on something if they can show the failure is the result of some modification like a tuner box, air filter, etc. I've heard of BMW denying warranty for something as simple as aftermarket tires or rims. But generally speaking if you remove the the piggyback then they won't find a trace of it after the fact. That is one of the big advantages of a piggyback vs. a flash tune where fault codes, etc, store true load values.