On GTX 780 (Ti) and Titan cards, one of the best launch configurartions seems to be

T number of SMX x 32

i.e. T15x32 for 780 Ti
T14x32 for Titan
T12x32 for GTX 780

Upped from 550 to 570 kHash simply by going from x24 to x32. autotune will currently not find x32 configurations.

Christian