In Australia, you can get a number of different fuels, and this also depends on what state you are in. Here in Queensland, the best two are BP Ultimate and Shell Optimax which are around 98 octane. Traditional "Premium" Unleaded fuel which you can get from most service stations is generally around 95 octane, with traditional "Unleaded" fuel being in the low 90's.
Personally I wouldn't run any car on anything less than premium unleaded, and if it was high performance or turbo then definitely I would choose one of the 98 octane fuels.
The 20v is a nice engine, however the 4AGZE is definitely the better engine. On paper the power figures are similar, but the performance of the 4AGZE is far superior.
Also, please be careful who you take advice from as it is not always correct!