Help me fix these artifacts

Hi, I'm new with xNormal, and just registered in this community to learn more about the awesome tool xNormal is.

I created a model in Sculptris, and reduced my model from 1.2M polys, to 12K. The normal map generated with xNormal looks great, but I found some artifacts in the extremes of toes and fingers that are very notorious. Please check out this screenshot, and my maps (color by Sculptris, normals by xNormal):

http://gamelix.com/demos/gigante/color.png

http://gamelix.com/demos/gigante/normals.png

The size of the model is large, to give you an idea when Imported in Blender it's about 20x the height of the cube in the default scene.

Could you give me an advice to get rid of this problem? Should I try certain configuration in xNormal, or increase the number of polys in these zones?

Thanks in advance! Cheers.