Pretty cool, essentially a factory tune for all existing and new MP4-12C's:

McLaren knows how to make a good thing better, as the automaker has announced the new
will boast 24 more horses for a total output of 616 hp. While potential customers are surely smiling, existing owners are too, because McLaren also revealed their cars will receive the power upgrade for free. The Ferrari 458 Italia makes 557 hp, for comparison.