Hey, I have an FG XR6 turbo. It does exactly the same thing. It only started after 3000klm, before that nothing.. I had it back to the dealer numerous times. They told me it is normal !!!!!even saying they have other demos that do it too.. I dont like it, but dont know what else to do. I took my car to a turbo specialist & took hom for a drive.. He said, yes normal, but for a car with a lot more k's on the clock The noise mine makes is like a siren, it does get a bit quieter after the car is hot..