I have the same problem coming from my left rear, sounds like a bbq igniter when i turn right at higher speeds. Dealership has no clue what it is and they assumed its the 2 piece rotor. I dont feel like paying to replace rotors/pads with 15k miles just to try and get rid of the sound, with no guarantee. They checked everything and nothing is broken/loose (I haven't checked myself)
For random, I noticed that the sound goes away temporarily after power washing the wheel. Once it dries the sound comes back.
My experience with this was that I was hearing this sound mostly when I didn't mount my R wheels. I took to the dealer, they had no clue, they could hear it while going in a circle and loading the car slightly. Once I gave up and put the carbon wheels back on and torqued to spec. No noise. Anyway, my story was torquing to spec. Whenever I torqued less than 130, I was getting the sound. I know it sounds silly, but I racked the car twice and could not see anything that would make this sound. It seems brake related, like when there's a bit more play in the tolerances, it drags and makes a pad drag a bit. Not sure, just offering my experience. :-)