The dealer has to prove that the problem covered by the warranty was caused by one or more of your modifications. An obvious example is that if you add an air intake and catback exhaust system and your radio develops a problem, the dealer can't say that those two mods invalidated the warranty on the radio. The federal law, which is called the Moss-Magnuson act, prohibits a manufacturer from invalidating a warranty merely because an add-on part, or a replacement part not bought from your dealer, was installed. The dealer has to prove that the non-OEM replacement part or added-on part caused the problem that the warranty covers. Adding an air intake and catback system designed for your Ranger is not going to cause any problem and is not going to be the cause of anything that goes wrong that is covered by the warranty. You are merely adding on devices specifically designed to get more air into the engine and get the exhaust out of the engine easier. However, many mods can cause problems in warranteed parts and invalidate the warranty on those parts. So you better know what the effect of any given mod is on the rest of the truck.
Bright Red 2003 Edge Plus, 3.0 liter, reg. cab, 4WD, manual trans., 4.10 rear end.
Mods: Speedliner spray-on bed liner. Air box mod. K&N drop in air filter. Gibson Sweptside single pipe catback system. James Duff traction bars (above the springs type). Delta Industries black polyethelene truck box (mounted on the driver's side of the pickup box between wheel well and cab). Hidden Hitch receiver hitch. Side window visors. Door pockets.