I have a wqeird question. the mechanic at the dealership told me that the noise coming from the turbo when u release the gas pedal, is from air rushing back out of it through the air intake tube. He said to install a BOV, and to do a aftermarket air intake kit, or custom, and this would solve the problem better. Also said something about adding a turbo timer in to keep the turbo spooling after shut down to cool it down.