You must have the first precat o2 sensors working, it's the after cats that may be turned off, as said above.

 

Perfect time to switch to some Desno Spark plugs, and aftermarket coil packs. They fixed my sputtering and made the car idle and run much smoother.

 

Your b1s1 and b2s1 sensors are still operating, they should not be shut off due to the fact that is the oxygen reference signal for fueling to the ecu. To prevent a catalyst ineffiency fault the programmer has turned off the monitor in the software. I recommend you leave your mass air flow sensors alone. Your vehicle only has 11000 miles on it, you have a stock airbox and no oiled filter that I know of, more than likely mass air flow is not dirty and I have never had to replace them at such low mileage unless an aftermarket air filter contaminated them. Your o2 sensors are likely damaged and fouled after running the leaded race fuel, and it is necessary to look at your plugs to see what they look like.. The adaptive nature of modern fuel injection could play a roll in you not having any fault codes, since the fault developed over the time you ran the fuel as did the contamination. Also some tuners shut off the misfire monitors with aggressive boost related tuning, others do not. Replacing spark plugs on a non turbo porsche is not a horrible deal, replacing plugs on a turbo is time consuming due to the number of things in the way.