Hello audi owners, for the people who will be reading this forum post and having similar issues like me, please note that after a lot of money and time spent (feel stupid saying it).. my issue was actually worn exhaust manifold bolts. I removed the turbo, re-thread 4 out of 9 bolts and used turbo specific screws i bought and the car is perfect now. The symptoms where at first after high boost or fast drives on my car, there would be a rattle/rustle noise at low rpm from 1st to 4th gear (not as much on 5th or 6th) and eventually upon cold starts the car would make a rattling noise similar to the timing chain but for a much longer duration. Throughout this ordeal i end up changing the following which might cause a similar noise fyi:
Timing chain (i did have the old tensioner P/N so i did not regret it)
Inlet manifold actuator control (sometimes the flappers might cause a rustling noise, however you can test them through VCDS)
PCV Valve (also causes a rustling, boost loss noise rarely)
Camshaft position sensor
i also suspected a loose wastegate flapper and i bought the Clip from Ebay
Hope this helps the trouble for someone else!