The Magnuson Moss act was put in place to keep dealers from denying warranty on non OEM parts like fuel filters and spark plugs. It was never intended to help someone when they installed performance parts. I'll say it again it will be up to you to take the dealer or car manufacturer to court. And they have a lot more money to fight you on it.
2015 Mustang GT Premium Sold
2011 Mustang GT Premium Sold
2003 Mach1 Sold
2.3 Whipple, fully built motor with all the bolt-ons 718 rwhp/735 rwtq Sold