log into engine control module with vagcom and the ecu number is reported top left.
6K0 as std ibiza, 8N0 a possible early S3 equivalent code they'be used in the 512k box

(same as Jabba's base file for IHIs in ibizas)
 
Looking at the fueling, its running about perfect (as in under 0.80v) at the lower revs, then its jumping to lean (above 0.80v) as it revs higher. That can cause the higher 'CFs'. 0.80 volts is perfect when at full beans.

All i can say is the map needs adjusting.
 
Its a narrow band tho so it wont give accurate a/f readings as the voltage switches as its only accurate over a small range of AFR around stoich.

Either get a wideband or forget block 031.
 
he had a big spike at 4k, the eliminator isnt that much more laggy, looks smoother though
 
boost for boost same comparison then to make sense of it all

it will be airflow related (exhaust manifold and turbo intake) I believe