From what I was told a few years back by my Chyrsler Service Manager is the following.

You are only covered if:
The mods are Chrysler or MB licensed and were done by a Chrysler Crossfire Certified Tech or a Certified MB Tech.

This may be dealer specific, the dealership that I took my Roadster Limited to was outstanding. They would install just about anything that I asked to and stand behind it, I had the MaxCare bumper to bumper warranty.