Personal experiences are subjective at best - too easy to think you are experiencing what you expect to experience. Confirmation bias is what its called.
You might like to watch this 5th gear
clip . It shows the high octane petrols producing an extra 2% bhp in return for an extra 6% or so on cost. And thats on a modern car engine which can adjust to the different fuels. On a car with a fixed ignition timing, there can be no improvement unless the engine pinks under low octane fuel.
