well i can assume yours is DPFI? 2 injectors vs 4. u cant do shit with that setup. not even chip it. i would convert to MPFI first. i cant think of a ECU that isint MPFI and VTEC. obd0 or 1 dosent matter as both famalys have, or ecu's that can be chiped to be, vtec ECU's.
actualy i just read the post and u said u have a A6 motor? in a hatch? must be the SI hatch. if thats true your allready MPFI. u lucked out bro lol.
the easiest would be staying OBD0 and getting a PS9 ECU. thats a automatic 90-91 EX and was the only ecu to run the A6 engine as a automatic for the sedans. there are porgrams u can use (chip the ecu) to make the auto output (one wire vtec) into a VTEC output. this wont be a stock program though so u may not pass your emmissions test. OBD1 would need a P28 ecu (92-95 EX/SI) but as there the single most popular ecu, they can be tricky to get / expensive. i got some P06 witch is OBD1 92-95 DX/LX and can be chiped and have the VTEC componets added to make a P28. I recomend going OBD1 as there are FAR more options of tuning especaly with a mini-me swap.
if u wanted OBD1 u need 3 main parts. OBD1 ECU, Distributor, and 4 wire O2 sensor. First the ECU is diffrent as it's is 16bit vs 8 bit. better resolution. like going from standard to HD tv. better control and mesuring. Second is because of the first the Distributor has the 3 sensors needed for the PGMFI system. these sensors have double the pulses on OBD1 vs OBD0. and lastly u need a 4 wire O2 as the ECU has a heater output for the heated O2. this is needed for proper poweroutput and on that old of a car it couldent hurt to change it anyway.
i can sell you the head with the obd1 distributor allready atachehed. i even have the OBD1-OBD0 harness and the Distributor Harness as there plugs are diffrent. what i DONT have is the manifold (your MPFI dont worry about it) and the 02 sensor.
if u want to read further or re-read what i just typed out go to
PGMFI.org 
