new kernel for the version in github/djm34
http://ge.tt/41D9Y872/v/0?c(it should work with metallicjames is you use in lyra2RE.cl the blake256 code of metallicjames version.
current hashrate on my 290x at 1030/1250 with -g2 -I20 -w64 1.46MH/s (average after stabilization) was 1.32MH/s before
donation welcomed: VyF9fXUSt5iZH6GuA8WvUw4NrVhcybMiLA
(even though it was a paid job... vtc has fall off

) so please makes updating the code worthy...
please also report problems as well as your speed (I can't reach the 1500MH mem clock... so I am a little curious)
I'm getting about 1.1MHs with 280x, but I'm getting a lot of "share above target" rejects on nicehash! Maybe 50% of rejects. This is probably the same thing others have reported, pool only sees half hashrate..
This is with latest sgminer from your github.