I've done several hours of research/reading on the topic on various websites, but I still can't find a conclusive reason for the problem. The "fixes" vary from letting the car break-in to installing a new turbo.
There are a couple guys that said installing a new DP fixed their problem, others that said the APR Stage I reflash changed the duty cycle on the wastegate and alleviated the noise, and one guy said installing his new intake fixed his.
Of course there are dozens of people with the problem and some were at the point of selling their cars beacuse of it. I suspect that there were at least a few that got to that point because they disappeared from threads they were very active on for months.
I'm going to start with the noise pipe delete and work my way up through a new intake, reflash, and new DP before deciding on the wastegate.
On a side note - with the noise pipe delete - do you expect to have issues at the dealership for warranty work? That would suck if they refused to do any work because of it!