[f5fstop]

Dealer full of BS.

Let me ask, where your wheels turned? Were you going up or down? Did you get a code? At anytime, did any of your wheels leave the ground with the stabilitrack turned off (manually or via the system).
I actually met up with the head of programming yesterday for the H3, he was in our shop doing some test cals on some vehicles. I asked him about this condition, and also a condition I had in Moab a few weeks ago (4-Wheel drive failed). For mine, I just turned off the engine and restarted and the system worked ok, happened three times over five days.
He admits that sometimes, the computer just gets mixed up and a restart will usually set everything right again. That is one reason why the cals change. As much testing as GM can do, we as customers seem to be able to do things they never thought of or tested for. Therefore, as time goes on, they learn these problems and adjust the cal to solve the problem.
He is always working on new cals, and when the cal is finished they must not only be tested, they must be certified if it is an engine cal.
Not saying that is your problem, but I would love to find out what code was retained in the PCM.
As for the exhaust, I cannot imagine what could cause a new cat back exhaust to cause the condition you had.