Just posted a optimized x13mod bin file for 7950 (and possibly 280x,290x and other 6xxx,7xxx)
compiled with sgminer 4.1.0 cat 14.6RC2 for those not wanting to upgrade to 14.6 RC2 at
https://bitcointalk.org/index.php?topic=666252.0Please post in my thread if this works for you

Baah... trying your bin for X13 and only getting around 2280KH or so at a total of 9.12MH for my 4x 7950's. Same rig gets over 14MH on X11 with another modified bin.