I've made experimental ECU with stock AFM, equipped with my external memory module + upgrade of the MCU (7433->5B25CT-1, which has +100 bytes of RAM).
Changes that were made:
1) Stock barometer MAP became external; can be easily replaced by an MPXH6400 (20kPa - 400 kPa)
2) A communication port with a bluetooth module / USB-RS232TTL for comms/firmware upgrade was attached
3) 5-pin connector was attached for an external hot-wire AFM (5 signals: +B, VG, THA, E2, EVG); ADC6 was used for this through 47nF/2k7 RC-filter
Stock code will be modified so that I will be able to record logs for MAP/hot-wire AFM to replace karmann vortex AFM either to a hot-wire type or to MAP.