928cs

Thanks.
It would be nice to know the real configuration of both car.
I suppose the GT3 has AC and Radio, and the RS has not.

10 GT3

With the earlier GT3s in other markets they had larger fuel tanks because they had more room for them as the GT3 is built on the C4 chassis. The space that was used to house the front diff was instead used to support a larger fuel tank. The reason it was not offered in the US is that the larger tank would not meet our crash pertection laws. You can retrifit your car to the large tank just by buying one through your Porsche dealer's parts department.