semicycler

This. The stock Porsche tune can handle as low as 90 octane without pinging but prefers 93 (see below)

Aftermarket prepackaged tunes are designed with a minimum octane rating. The highest performing street versions usually target a 93 octane minimum. But they offer versions with a 91 octane minimum too. The various tuners will have about six or more flavors for your make/model depending upon what intake/engine internals/exhaust mods you have installed along with what minimum octane you use. See VR-Tuned's website here for an example, notice the form you fill out stating the octane you use: https://www.vividracing.com/catalog/...150773642.html

Then there are custom tunes done on your car by a specialist with the car on a dyno. This class of tunes is really only for the non-standard mods or if you happen to be the first one doing a particular mod so the tuner can get a baseline.

Bottom line: you have a tune, verify the minimum octane required for that tune. If it's 93 and you use 91 you will have pinging. Either replace the tune with a 91 version or go back to the Porsche stock version.

the_buch

^^ thanks for this, including the guidance on ethanol-containing fuels. Most stations here on the west coast of Canada use up to 10% ethanol. Fortunately, Chevron still carries a 94 octane premium with no ethanol :-)