usually depends on your dealership. but simple stuff like intake and exhaust and dp will not void your warranty. what my dealership told me is that if i touch the intercooler piping, my warranty's gone. a boost controller will void it as well.
Legally there is a law to prevent them from out right voiding the warrenty due to aftermarket modifications unless it is directly related to the failure.
And if the dealer installs the part then it can never void the warrenty.
But overall it does depend on the dealer and service manager if they will put up a fight.
Been discussed a few times here but that is a quick recap of it.