Even though that may be so, I can see where some of these warranty denials could possibly end up in court since Ford specifically states the following under What is Not Covered;
Damage Caused by Alteration or Modification
The New Vehicle Limited Warranty does not cover any damage caused by:
• alterations or modifications of the vehicle, including the body, chassis,
electronics or their components, after the vehicle leaves the control of
Ford Motor Company
• tampering with the vehicle, tampering with the emissions systems or
with the other parts that affect these systems (for example, but not
limited to exhaust and intake systems)
• the installation or use of a non-Ford Motor Company part or software
(other than a certified emissions part or software) or any part or
software (Ford or non-Ford) designed for off-road use only installed
after the vehicle leaves the control of Ford Motor Company, if the
installed part fails or causes a Ford part to fail. Examples include, but
are not limited to lift kits, oversized tires, roll bars, cellular phones,
alarm systems, automatic starting systems and performance-enhancing
powertrain components or software and performance “chips”.
Peter