from my POV history of x11/13 mods is:

After girino's x11 with 2%,  a guy hacked his exe-  and we had x11mod kernel .cl file , 270K big - hacked from girino's exe
Then came a x13mod, based on this 'hacked' x11.
Its 281KB big .cl file
This x13mod works ok on 5xxx and 6xxx - increasing speed with 20-30%

Then, Girino released his x11 cl (~ 30Kb), then came your x13mod
Its faster, but doesn't work on older cards
I supposed you are the author of first x13mod :/