Is there a way to add ML to the car if I didn't get it. They were charging me an extra 4k for it which was ridicuous. If I can, would it even be worth it? Should I get another system?

 

This has been discussed just recently.

You can theoretically add the system, but it will cost thousands of dollars to do so, because the ML System is a system, not just one part to install: it's a fully integrated system with different speaker set-up, DVD/CD player instead of CD player only, and has a different amp.

Do a Search and you'll find many threads on this topic. Good luck!