So I just wanted to follow up, as I appear to have an answer but not sure if I'm happy with it.
The answer is..."operating as intended." Apparently this pretty annoying noise is the twin turbos normally functioning. Hm. Ok, I am trying to ignore it, but boy is it annoying when I'm driving at 60mph.
Does anyone else have a similar complaint? I've had the mechanic look at it at the dealership where we bought it, and then brought it to the Ford dealership. Both say the same thing. Is this vehicle just equipped with an annoying sound?