It looks to me like a lot of that seam is in the diffuse map. I think if you work that out first, the normal seams will be less noticeable. It also seems like youre doing an in-viewport shader. I think those tend to show the seams more easily.
MoP - I've tried a couple other shaders/materials and the seams still show up. Sometimes to a lesser extent but still pretty bad. aesir - There are seams in the diffuse map but the normal map is doing most of the damage. Ben Cloward - Thanks for the link Ben, lots of good info there. J.I Styles - Hmm... I've been breaking…