So no easy way to get past the MAF limit?
What IS the limit of the stock AEB MAF (flow and Volt)?
Can the volt me logged (VAGcom for example)? Measured? (how, what wire)?
How can I tell if I maxed out the MAF?
Everything can be done with the right tools, but there are no publicly available ones for this ECU.
IIRC the limit for the stock maf in it's stock housing was somewhere around 240hp.
The VR6 housing allows to go further than that.
The VAG com limit you will find if you look at the OBD I protocol and how the MAF value is calculated from the two bytes.
That said, don't focus on the flow numbers too much in VAG-COM, there are very few aftermarket tunes where the MAF is scaled correctly.
Basically, to tune this ECU you will need a 16 bit emulator with some creative cabling and you will need very good understanding of the old school data logging protocols.
Either go to a professional with this who can do a live remap (do not settle for someone who just changes chips) or go with a standalone ECU.
If you just need this to tune your own car, it's a huge waste of time as the hardware requirements to get into the game are pretty steep with this particular ECU.
An option is to swap to an AGU ECU, that has a full DAMOS available and is OBD flashable and is plug and play compatible, but again, you won't really have any data logging besides VAG-COM unless you are willing to implement the mcmess protocol.