Lift kits on trucks change the angle of the driveshaft and can cause U-joint and powertrain issues. Slamming a vehicle drastically changes alignment angles, causing rapid wear of automobile tires. Another difference between suspension modifications and the upgrades mentioned above is the amount of work required to return it to its original factory condition. How Car Modification Affects Warranty and Value My basic advice is that whenever you make a modification, keep the original factory parts. You may wish to restore to original condition for exchange or private sale. Remember, beauty is in the eye of the beholder and those shiny 22-inch wheels may not be what the next owner is looking for. As for warranty coverage on a modified automobile, the decision whether or not to cover malfunctions will always be up to the dealership. Technically, any modification will void the warranty. However, if your factory installed stereo stops working, a modification to the cold air intake should not void the warranty on that radio unit. However, it is up to the dealer to submit a warranty repair on your behalf. Many car owners will undo modifications before taking the vehicle to a dealership's service department, just to be safe.