Originally Posted by APM Racing
There's a coupler that gets folded under the throttle body, they get destroyed with oil, kink and leak, happened a few times with cars that we worked on from the dealerships. We work with a few local ones fixing the cars that they don't work on because taking it an actual dealer is so much more money so you start to learn those quick fixes.
You can pressure test the system and it'll sound normal, until you'll randomly touch the intercooler or bov hose, then it'll squeel like a pig, then it'll be fine.
Check it out, it's the most common issue we see with them.
The fact that your having this issue with your foot coming off the throttle (which it seemed in the first vid), would suggest the bpv hose itself has a kink or something that leaks.
The wasegate noises are much more pronounced when an aftermarket downpipe is installed, and then even more so when there are small leaks in the gaskets as with heat expansion and pressure can cause mild expansions.
^this! mine just failed as well (throttle body side) and dealership is gonna repair. Thank god for the warranty! O and thanks to this thread because I had to suggest they look at this when they couldn't identify where the noise was coming from! Thanks all!