I did mine at inskip in RI. I took in the car telling them it was wastegate rattle. Showed the tech when I got there and was given a 2011 328 e92 xDrive for a free loaner (paid $12 fuel charge and had the car for a week). They ran the BMW tests and told me they were going to regulate the wastegates (which disappointed me quite honestly), then the next day they called back and said they were replacing the turbos.
Overall, I was without the car for a week, was given a great loaner, and was treated very well. I have always had great experience with inskip.