This is not me assuming you're stupid, it's just a simple step that can be missed. You did prime the turbo with oil prior to starting the car? By either disabling the injectors and letting it crank for 30sec to 1min then starting the car.

Other thing could be a boost leak and over speed of the the turbine, or you could of had some actual compressor surge

 

Check. I filled the turbo oil inlet with oil before installing the banjo bolt. When everything was wrapped up, I cranked it 3 times with the gas pedal floored (the car goes into flood clear mode like this, and will crank continuously for about 30 seconds each time).

No boost leaks as far as I'm aware, although I've had the charge pipe pop off on me... I had to limp the car to the nearest off ramp.

Haven't heard compressor surge, nor do I know what would cause that on a stock turbo set up.

I need to find the root cause before I replace this turbo, or else the replacement will just die another short death.

 

Could a bad tune kill a turbo? I noticed a lot of backfiring downshifting 3 to 2.

 

Just checked the PCV valve. Its fine /facepalm

 

Can a plugged cat cause this issue as well?

 

It seems to leak only when I'm boosting hard. What could it be? How can I be sure its the turbo, and not something else?