I just read the ECU sensor with the Consult. I've seen as high as 93*C (200*F) on an SR20 when doing pulls on the dyno, and the stock gauge still read in the middle / half way up (no movement). 260*F is around 127*C. If you're really getting that high, I'm pretty sure that your coolant would be boiling, and/or your headgasket would be writing it's will.

edit: I'm going add a relevant title to this thread....