Found out I accidently unsubscribed from this post. When I installed the Dp for the first time I did not have any issues whatsoever. That was with McDowell stg 2 tuned. No over boost issues then. After my engine rebuild and BNR 20G with ported wastegate. I was having over boost issues. But they were not related to the Downpipe at all. The issue with mine was the actuator arm after the wastgate was hitting the heat shield on top of the turbo. I was concerned about the wastegate not opening due to clearance with the DP but that was not the case, as I took off the down pipe and hooked up an air compressor to the wastgate and physically saw the flap stay closed but the whole heatshield shifted when the air was applied. I marked where it needed to be cut and removed about a 2-3 inch section from the heatshield. After I installed it again. My overboost issues were gone.... I have the Original design for the downpipe. Not the Group buy one. And I'm also at elevation. About 3500ft.