I did purchase the warranty. So far my thoughts are about taking the car back to CarMax and asking to get out of their warranty. I have had heard of people being able to cancel their warranty and get (at least a prorated) refund. My argument being: If CarMax is willing to sell me a car with non-stock original parts on it...they'll probably install those crappy parts on the car again. And I won't stand for that.
DCV: to your point, in any case the car will NOT be going back to CarMax for repair.....everything from Cadillac from now on! And that will most definitely be more expensive for CarMax in the end.
I don't know how an exhaust would "SOMEHOW" get damaged
Chris E