How much RAM do you have in your system? When I firs purchased my rig I was told by a friend that I needed more system RAM than I had total GPU RAM. I didn't believe him, but for some reason apparently he's correct and having less system RAM than total GPU RAM can effect hash rate negatively. I run 16GB of System RAM, but another difference we have in our setup that is more obvious is that I'm on Win7 running 13.12 CCC drivers.
Just noticed as well that you're using a miner source from "Benmagro", I'm not sure who that is, but try compiling Lasybears
sph-sgminer_x11mod_b2_2min_SICK version, as that is the one I'm still using. If you search near the beginning of this thread I believe there are some instructions for compiling the source on BAMT. Good luck!
I have 8GB of ram on my systems, a couple have 4 but there is no difference in hashing amongst those. I will try one with 16GB and see what it does. The BAMT 1.6 version I am using has the 13.12 drivers installed. I will take a look at the SICK version lasybear that you mentioned. Also going to try the sgminer5 that is out that supposedly has the lasybear forks built into them.