Why 98 matters on a tuned car
Many of the files in our guides are written for 98 RON; Posaidon, for example, lists 98 RON for its C63 software, and US tuners' 93 octane is about 98 RON. On lower-octane fuel the engine computer pulls ignition timing to protect against knock, so you lose the power you paid for, or worse. Run the fuel your file was written for, and ask your tuner for a 95 file if you want to save at the pump.
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