I add the hair in ZBrush as fibremesh. In the beginning I made the strands wider and added a hairmask of several hairs, but you get repetition. Now I just use unmasked hairs, though with as little as possible polys lengthwise. This hair is 20Mb. For curly hair it might triple or worse. If I really go off, I can dubdivide the guys and sculpt a lot of detail in, and add very detailed hair, but for now this is okay.