/3/ - 3DCG

So I'm trying to bake a World-Space (bent) normal map from a single mesh (no highpoly), and render to texture won't work as it just gives a flat image, however i was told making a Mental ray "Ambient/reflective Occlusion material" with type set to "bent normals (world)". When i did i got what I wanted except rendering was quite slow and I got a lot of grain as seen in this picture.

I attempted to use xNormal with an OBJ file of the same for the HP&LP slot and was faster and was totally smooth, no grain. I also tried a third method of Blender + TexTools plugin with the Bent normals bake button that also produced a smooth no grain result fast.

So is there a better way within max that im missing? All the search results I can find are this slow method.