im no expert but i did have a brand new ford pickup last year, and wanted to lift it and put wheels tires,exhaust, the whole nine yards. i was told the same thing that if you didnt get it done by the dealer it would void waranty but when i asked the service manager at the dealer he told me that it would not void it but if somthing were to go wrong with the pickup and i put it in the shop and they traced it back to being caused by the lift, or any other mod that it would then void it! (sorry for the runon sentence lol)