I have a 2014 GL 450 with 50k miles. It has had an intermittent check engine light that always comes back turbo underboost. After repeated visits to the dealer with no diagnosis they kept it. Told me it could be a long process of troubleshooting. A week later I called for an update and was told it’s a big deal, smoke test, up to pulling engine. Then several days later, yep MB is going to replace the turbo boosters. I might mention I have the CPO warranty and that in the face of all the lights the car drove fine. Pics below indicate its current state. And now I’m panicked that it can’t possibly be the same after such extensive disassembly. What would you do? Do I trust that they know what they’re doing? This seems to have escalated quickly. Sell it ASAP? Drive it for a bit and see how it does? I’m feeling a little sick and maybe I’m over reacting. Be mistrustful that a big job was under taken because the customer isn’t paying???