i dyno'd 252hp/290wtq on my k03 and that was on a hot ass day with humidity (temps were almost in the 100's now if i go put in some high octane fuel and go now with cooler temps and less humidity I'll be very close to 270whp and i'm dsg.
No you won't, i'd say you will be still around the 252 hp. The boost isn't that high with a ko3 so temps won't make a whole lot of difference IMO. Mine roughly makes the same hp regardless of outside temps certainly not 20 hp differences. If your car is making 270 whp i'd have a spare turbo in waiting if i were you.