LCR reads boost from the OBD port, that's how vag-com logs are obtained
Yep, been spending my afternoon doing a bit more digging.
The AUQ, AMK and BAM engines all report back to VAGCOM the boost using measuring blocks 115-3 and 115-4 (boost specified and boost actual) - however there's nothing I can see which says what actual ODB PID they map to - I'm guessing the LC ECU also reports the boost actual using either a known PID, or the MAP sensor value is then adjusted to suit.
I've confirmed using a few different ODB tools that on the LCR, the MAP sensor returns no data at all using the standard ODB parameters ...
So, all I need to do is work out the PID that 115-3 and 115-4 map to in ODB terms ...