I had my car tuned in the US with Sunoco 93 octane. Here I use PetroCan Ultra 94. When I was in California and needed gas I switched maps to my 91 octane map and used Shell 91. If you have a custom tune get a 91 octane map. It's a piece of cake for the tuner to do.
If you're running a stock tune, you can switch between 91 and 94 octane without issue.
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