TT Boost Issues

[Mulyac]

Hey all, got a problematic 2002 AUDM Rev D B4 with boost issues. EJ208

When i bought the car it had no boost and a suspected fairly recent engine replacement (engine codes etc dont match up to paperwork). After fixing various oil leaks I focused on getting the turbo system working. I managed to get the primary turbo boosting to about 14psi and the secondary boosting to 9/10psi. Surely the twins dont boost less than the primary?!

What i've done to get to this point: (Every part replaced was from a confirmed working 2001 B4)
- Replaced every vacuum line in the engine bay, making sure the replace pills (line near BOV was missing one, was only able to find a 1.5mm replacement)
- Had engine out for other reasons and checked turbos, both spun freely with minimal play
- Put a known working intercooler with silcone pipes
- Put a new GFB BOV on the intercooler
- Checked lines from vacuum tank to BBoD (holds vacuum, hisses when removing a hose)
- Made sure the Exhaust control valve was functioning and adjusted
- Replaced that U shaped thing that sits near the secondary turbo and connects VIA vacuum line to the differential pressure sensor
- Replaced Differential pressure sensor
- Removed BBOD and found a broken vacuum line, fixed line and didnt work
- Cleaned all solenoids in the BBoD and the boost controller solenoid
- Found the exhaust gas control solenoid inside the BBoD was broken, replaced and turbos have started to work

Im pretty sure I have checked/replaced most things that would affect boost but it still seems to be behaving funny. VoD occurs over about 300 RPM from 4000ish and the secondary turbo gets hot after hard driving.

This issue has me a bit stumped and I would prefer to not need to throw stupid amounts of money in diagnosis if its a simple problem that im just overlooking. I've asked around on more local facebook groups to no avail.

Thanks for any help!