elRey Wow... that's great, thanks for sharing.
Would it be possible to control the turbos without the custom coding using the MAP in the stock location?
Sure, but not separately. And if you can't control them separately you can't specific at which PR each operates. Thus, you have have to rely on their sizing.
There are a few ways to control them. You can have one N75 control both. Two N75s, one for each but driven by the same ECU PWM allowing different boost signal sources.
MBC on one and N75 on the other. I'm sure there's more. All of which require different KFVPDKS,KFLDRL,KFLDIMX, and PID calibration. However, I want the ability to specify the PR the LP turbo will operate at independent of it's sizing compared to the HP turbo AND retain minimum base boost for drivability without depending on KFVPDKS heavily.
Are planning on implementing 5120 hack?
I am planning to. I'm just not looking forward to the work. I have done it for my Jetta Wagon 16vt and it was tedious. I'd rather do the work myself instead of relying on what's out there. I currently have a 4bar in the stock location and a 3bar between LP and HP turbos and wiring in place to support 2nd MAP and N75.