i don't see how they can quote power figures for a map not developed yet?
They will be guesstimates mate, at the end of the day a RR isnt accurate so they can quote what they want. Going by the fact the new R wont be using the mk6 engine (ed30 is the rumors?) i doubt its more tunable than the mk5 so probably more like 250bhp, similar to the current engine.
Who knows though, might well do 270bhp for all we know?