I've been making a simple displacement map in ZBrush for a model I started in maya, but when I port it over, the object looks rather "fat" I've taken the alpha multiplier into account (multiply/divide note from the file to the displacement map), but I think my problem stems from the alpha map base colour being 50% grey. doesn't maya do displacement from black? This would explain why everything is getting displaced, even the stuff that shouldn't be.

can I adjust the maya displacement map so that it works from 50% grey rather than black (so I can have some negative displacement too?) or have I got to somehow get the base colour for the displacement map from zbrush to be black?