As you can see in the image above, there is a big change in shading past the uv island on the end. i have no idea what caused this, but I can reproduce my steps as best i can.
Model high poly in zbrush
Duplicate and decimate the duplicate
Export both to 3ds max and align them
UV the low
make a cage by duplicating the low and adding a push modifier
export the low, high and cage
bake in xnormal
add material in max with 100% normal strength plugged into a normal bump with the source linked to the texture
Change viewport to realistic materials with maps
No idea why this is happening. I used tangent space any ideas?