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The engine is tuned for both or it would only contain one timing map.. There is a literally tables called High Octane and Low Octane timing table.. Its designed to use the Low Octane when using 87 and 91 and High Octane when using 93.. There are things built into the stock tunes that vary what your ECM is doing based on Octane.
As for the pinging Questions above yes when I ran a tank of 87 I would get sporadic pinging you could hear in the cabin on tip-in/Take off you could also very specifically feel the performance loss when it happened due to the engine pulling timing for the knock. Like i said after that never ran 87 again. Could have been bad gas could have been the car not being used to 87 ECM have learning functionalities as well for fuel and by changing up the octane you are changing up the habits and the computer has to relearn.
There is long term fuel trim learning
There is learned knock
as well as other things..
I am by no means a professional tuner or anything close to it but I understand the inner workings of our Computer pretty well at this point.
Also this time of year you will notice less difference between the AKI of the fuels because its cooler outside so your intake temps will be down and the fuel is less likely to spontaneously combust causing knock.
How much difference in performance I cannot tell you but 93 is definitely safer for your engine if you are running it hard.
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