91 octane maps are different from 93 octane maps, there is quite limited adaptation there as I understand this, where exactly I did read about that I do not remember now of course but it was so when I was researching different options for ECU flash.

It also was on several forums, that fact that 997 stock is tuned for 91 octane. If it is not - you`re first who wrote about that.

 

This is from AWE FAQ:

Fuel composition: most modern vehicles have multiple ignition timing maps to allow the fuel injection ECU to compensate for the varying qualities of fuel found in their intended markets. For example, the US Spec Porsche 997S has four ignition timing maps to choose from depending on the amount of measured knock activity present. Thus, on 91 octane RFG (Reformulated Gasoline) fuel found in California and other parts of the US, the fuel injection ECU jumps to a less aggressive ignition timing map, resulting in a lower power output than on the 93 octane fuel found in other parts of the US. On some highly modified cars, fuel octane and composition can become even more important, and the positive effects of high octane racing fuel can make a tremendous difference. When viewing a dyno sheet, it is best to determine what fuel the test car was run on.

http://www.awe-tuning.com/pages/faq/...ain.cfm?FAQ=22

BTW: the 'specs' of 355hp etc. that Porsche uses are based on 93 octane maps