back when I had my 125i (also N52, 218hp) it clocked 245kph according to the speedo (which actually was the official top speed). after the tune to achieve it's full potential (as it basically is a software tuned down version of the 130i with then 265-270hp) I was able to achiev 265-270kph on the speedo but it took forever because of my 19" rims...according to gps this was real 260kph...I don't know if there was any speed left