Projected Normal Map on Rocks

So this is the result of a Maya cube taken into Z-brush to brush it into a rocky geometry, then exporting said geometry in a low, medium and high polycount (160, 640, 9900 triangle count). Next I took all of the models into 3D studio max, selected the low and high poly model and derived a normal map (high to low).

Deciding to see what it looks like I then created a material with a bump normal map, which is the result below. The texture is a quick random texture from the site highresolutiontextures.com.

These are the models and the textured versions:

The Normal map looks like the following:

Because I projected it all of the high resolution details are embedded within the uv unwrap of the low poly model. I suspect the hard edges to come from the hard edges in the low poly model. Must remember this for the next time.