You are actually at the very cool end of the spectrum.
I bet if you started to push it above 4.5k rpm for a while it would hit 250-260.
Mine hit 255 after an hour of driving in DS mode on and off with pretty spirited accelerations.
I don't doubt it if I consistently redlined it in 90 degree temps it would hit 280-290. Definetly something to keep an eye on with these engines.