I assume you installed he Solution B Pedders sway bar Package? If so., take a peek to make sure the sway bar itself is not contacting the inner part of the frame. the potential contact area would be where the ABS line attaches, then straight down.
Also GM now has a first and second design upper front spring insolator. The second design is blatantly obvious. It is a white/beige piece that sits under the upper spring mount. With our Xas we remove both styles. This is for future reference.
GM has issued PI on the front noise concerns. They are at the stage where the are collecting data for problem solving. I believe they issued it in March to all dealers. So GM is being very active in trying to identify the source. We have to be patient on this.