We have confirmed information that it is possible to change ignition map in our cars by means of jumper. There is special service jumper called "octan selector" and it allows to select mensioned ignition map. Default map is made for 91 octan fuel. It is possible to switch it into 95 octan and also into 87 or 81 octan. The connector is located near the ECU - right hand side in the legs of passenger, under gray cover. It is very close to ALDL connector. The one is white in colour and has 3 wires - white/black, black (ground), white. The black wire placed in the middle is the ground. Sometime one is hidden under ECU. Possible setting below:
1. The wires are not jumered – 91 octan (default setting)
2. white/black to black - 95 octan
3. white to black – 87 octan
4. white to black and white/black to black - 81 octan
If you change the selector into 95 octan , your engine will be much more silent and flexible. The fuel consumption should be also little bit less.

Here are pictures and thread in polish.
http://motonews.pl/forum/?op=fvt&t=5776 ... &start=260
http://motonews.pl/forum/?op=fvt&t=5776 ... &start=120
Similar issue accords to Deawoo Nexia but the colours of wires can be different. Simply the ECU unit is the same type (IEFI-6)
Regards
PAwol/Poland