a quandry....
According to the manufacturer's specs, if you mod anything, then the system you made the modifications to is now void under warranty. However, and I say this strongly.... It can also apply to systems that are affected by the modification.
For example: You add a lift and bigger tires... 6 months later, you have to replace the steering pump. Some dealers (not all) will argue that the increased weight of the tires and wheels over the stock size/weight caused premature failure of the pump and thus is not covered under warranty. I have known people who lifted their jeeps and threw U-Joints or driveshafts, and the dealer refused to service the vehicle under warranty because the angle of the lift placed the shafts and joints at a more severe angle causing them to fail.
Bottom line, it is most likely a dealer call, but any system affected by the lift may be void under warranty (this would include, but not limited to the brakes, steering, drive shafts, tranny, diff's, and the electronic systems controlling these areas)