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Back in the late sixties, high performance engines from the factory came with a C/R 10 to 11.5. We only had distributors to regulate the spark and advance. Higher octane fuels helped us get by these limitations. To get the best et's, we would run the timing as close to detonation as possible. Modern engines with computerized ignitions will do whatever it takes to eliminate detonation. A much better set-up. Our cars are shipped from the factory to satisfy a majority of buyers. That's why the aftermarket has many computer options for the performance minded. If you run the suggested fuel with an unmodified engine then you should never have a problem. In fact higher octane could cause you to lose performance as the burn would be incomplete.