Will the change in Dave Andersen's code on github increase the hash for a 660ti card already running at 290kh???
you're already running it. It's in the 2013-12-18 release.
The github version adds maybe 10 or 15 kHash/s more (by supporting the -C 1 flag). It will be in the next cudaminer release, toggether with scrypt-jane (Yacoin) mining support.
I just mined my first Yacoin block SOLO. One 660Ti plus 2 GT 640 cards add up to 4.5 kHash/s, which is significant hashing power for Yacoin (the whole Yacoin network is around 1000-1500 kHash/s only, with blocks being generated once per minute.)
EDIT: I was trying to use the tesla kernel. It doesn't appear to like Jane. I can squeeze out 2.3 KH/s on my gtx 780 using K9x2. Going to keep tinkering.