Use your borescope to inspect the compressor wheel on your VW Tiguan’s turbocharger while you have the diverter valve removed. Continued...
Also, I think I may have somehow solved both my shifting and boost issues at the same time by replacing the original shitty diaphragm style diverter valve with an improved piston style valve.
After install, the improvement in drivability was immediate. The car started shifting correctly in normal Drive mode again (like pre-APR tune) and the car just feels better overall. For a while there, I had to drive in Tiptronic or Sport just to prevent all sorts of shift flaring and whatnot. It was weird as hell.
A while back, I took the Tiguan to the local Audi/VW/BMW/KIA dealer and they wanted to straight up replace the turbo. I hope that’s not the case just yet.
Oh, did I mention I got my Tiguan APR tuned in July? Stage 1 - 91 Octane woo woo.