Remember with the whole warranty thing: the dealer has to prove that the aftermarket part caused the problem. That sounds good in general, but some dealers are pretty shady. They might say that your ECU upgrade caused ___ problem to happen and then you're screwed.
When I installed my CAI, I called the warranty service and they said that it was ok. As long as I replace the filter in my stock car with another filtration device it wouldn't void it.
Happy modding
