If talking to Chrysler doesn't get you any help, tell the dealer that you will be happy to have your lawyer forward them a copy of the Magnuson-Moss Warranty Act of 1975. It states that they must prove the modification was the cause of the damage, or honor their warranty.
Magnuson-Moss Warranty Act - Wikipedia, the free encyclopedia
15 U.S. Code Chapter 50 - CONSUMER PRODUCT WARRANTIES | LII / Legal Information Institute
Magnuson-Moss Warranty Act - Wikipedia, the free encyclopedia
15 U.S. Code Chapter 50 - CONSUMER PRODUCT WARRANTIES | LII / Legal Information Institute