The argument could be made if you mess with your transmission setting and your transmission malfunctions. They can deny your warranty claim for that item. Argue, debate, whatever.
Your vehicle will sit for months (or WAY more), until it is hashed out in some type of legal environment, which *may* require their lawyers and your lawyers, and some type of experts on both sides. If you win, you may still have to pay for your laywers/expert's time. If you lose? You *may* have to pay for theirs & yours, and still have a mashed transmission.
I have never done a Mag/Moss act in a courtroom, but I have had difficult dealerships and done the courtroom dance for unrelated lawsuits.
I believe the M/M act was designed to protect other companies producing similar parts and fluids, so dealership A couldn't say, well you didn't buy our oil, you used B's oil, and now we deny your engine claim.
I've been doing this 26+ years on 15+ forums, and never heard of anyone fighting this in a court battle (modding for performance and having dealer warranty denied). I know a lot of folks who were denied warranty for their performance mods though...YMMV, I would wait until the vehicle is out of warranty first. A lot of controllers actually make you "agree" that the mods you make are your responsibility if damage occur, or have other banner warnings.
YMMV, but I LOVED my Predator on my old Expedition-it solved shift slop, tire difference, woke up the engine on 87 octane, raised the limiter, etc. It was well out of dealer warranty though.
Good luck-
