Stupid dealerships doing stupid things does not trump US laws or standards.
Sometimes you need to fight for your rights if a privately owned company is taking advantage of you, this is nothing new.
If you do something to modify your car\truck and it causes damage don't expect the warranty to cover it as you are in the wrong.
People here will debate this till the world ends.
If you are really concerned call an attorney in your state and ask them if it is legal, and how much it would cost to hire them if denied a warranty claim in the future.
Here is some additional information if anyone wants to read it from the Auto Care Association.
The Magnuson Moss Warranty Act (MMWA) prevents manufacturers from using disclaimers on warranties in an unfair or misleading manner.
www.autocare.org
"get educated
The Magnuson-Moss Warranty Act prohibits product manufacturers from conditioning consumer warranties on the use of any original equipment part or service. Furthermore,
a manufacturer can only deny warranty coverage if it can demonstrate that a non-original equipment part or related service caused a defect to occur in the original product. In the case of motor vehicles, new car manufacturers have ignored these conditions outlined in Magnuson-Moss and have misled consumers to believe that they must have dealer service shops install only original equipment replacement parts or fear having their new car warranty voided."
This is another website that makes some good comments too (it's a law firm's website not the government)
Modifying your new car won’t automatically void your manufacturer’s warranty. But it may cost you depending on the mod. Here is what you need to know. I got a few questions the other day about vehicle modifications and whether a manufacturer can void your warranty over them after I mentioned the...
lehtoslaw.com
Many modifications people do to their cars fall outside of the “article or service” contemplated by the statute. Suppose you loved the way Vin Diesel could pull wheelies in
13th gear in his Charger and figured a little of that “NOS” would do the same for your car. Even if your little four-banger won’t pull wheelies in any gear, it now puts out a few more horses than before. So, if you find the transmission spitting out teeth like it’s been punched in the mouth by Mike Tyson, you can bet the manufacturer might blame the problem on the increased power being fed to the trans.
The Magnuson Moss Warranty Act requires manufacturers to honor their warranties and auto manufacturers only warrant their vehicles against manufacturing defects. Y
our claim here could be denied because the failure was not due to a defect in a factory component. It was caused by something added to the car: the nitrous oxide injection system which was not part of your car to begin with. That system caused a non-defective part to fail.
Your mod did not void the warranty. It’s just that the failure was not caused by a factory defect.
Learn and understands your rights and don't trust anyone's word on the internet, myself included.