The dealer is actually pretty wrong. At least from my understanding. I had a 6 inch lift installed at the dealer (they did it and was this way before I purchased it). The lift components that the dealer used ( likely a third party ) are still under their own warranty, and the truck it self still has it's own warranty. If you're engine blows up for instance, the lift didn't cause that. the only way a dealer can say no warranty claim on something is if the lift kit directly contributed to the part being warrantied. I.E if your upper control arm breaks because you wen't off road to get to a job site, and you have a lift, they could possibly say the lift did it. though, even that might be sketchy. The normal warranty still remains on lifted trucks, even if the dealer didn't install the lift. I've had my truck in for numerous items and they fix them every time without issue. If you check out geico, they actually provide a mechanical breakdown service for NEW trucks under 12k miles, and they will cover lift components. I had my rear extended break line break, and they purchased me a new one