Hi, I have seen couple tutorials on YouTube and elsewhere about retopolgizing in ZBrush, all this is great for changing the flow of geometry but is there a way I can actually project a Tangent Normal Map from High Poly model to its Low Poly version like it is with xNormal ?
I believe in Zbrush you’re going to be limited to using the subdivision levels to bake a normal map. You could try subdividing the retopo’d mesh a few times, projecting the sculpt detail onto it, and then creating a normal map, but I prefer to stick with xnormal as it offers a lot more control along with the possibility to customize the tangent basis to fit the renderer.
I thought that this feature is not yet available, maybe in ZB5 anyway, what you suggest is not as bad anyway the only drawback with this method is that wile retopologizing you would have stick with quads again so it would subdivide properly to get detail projected. Yep xNormal stays then 
I recently saw this TopoGun it seems pretty handy, anyone tried it?