This car is ready for more power, but Audi strategy is just little dumb. For them "smaler" car must to have smaller engine.
So 4 series must have smaller engine than 5, and 5 smaller than 6 and so on.
They just dont want to make their own cars compete with themselfs.
So even they cloud make 555 hp RS5, they will not do that, beceause thats reserved for RS6.
So litteraly: S4 have 333, RS5 444, and S8 520.
But Audi, i want small car with enough power. Who want to race with S8?