After a few days of thought, experimentation and research, I've come to the conclusion that EWGs (electronic wastegate actuators) are just noisy on close by default. Specifically, I believe that the VN's EWG is the reason for the noise in this thread. The noise is like a rattle that seems to happen very briefly when the throttle is abruptly released after boost is built (wastegate shuts closed). However, since there is no spring tension on the wastegate (the only tension is from the little motor in the actuator), this enables the exhaust flow to momentarily disrupt the wastegate seal, causing a tiny vibration. I've tried everything, from JB-welding my turbo heat shields, to extending the wastegate actuator rod to increase "preload" (which I'm not sure even is effective for EWG actuators), nothing could resolve the noise. I've also looked through other car forums. It seems like any modern turboed car with an EWG (Type R, STI, etc) has some sort of issue like this. I am still under warranty, so I'm going to reset the wastegate arm to its original position. I guess I'll go to another darn dealer in hopes that they are not deaf and can hear the noise. If another one tells me that it isn't noticeable I don't know what will stop me from exploding at them. This sound is driving me crazy. If by chance the dealer CAN hear the noise, I'll post their opinions on it here.