Imagine you bought a new car, which was described as having a 340 horsepower 3 litre engine. You've owned the car for a few months and had no issues with it.
Then you discover in the news that it's actually a 300 horsepower engine, since the company made a mistake when advertising/marketing the engine.
You'd sure as hell want some compensation, either a replacement car of the correct specification or a refund, regardless of if you ever fully utilized the full power of the engine.
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Except in that analogy I would say its more the diameter of the fuel line than the horsepower of the engine.