this is happening to me aswell!
whenever i let off the clutch particularly sharply, a big clunk sounds like its coming from the rear/mid section. I'm gonna get it on the ramps tomorrow and check mounts for gearbox and engine, i think this may be the issue. If not, i think CV joints may also cause a noise similar when turning, although mine doesn't seem to change whilst turning so i think i can rule that one out.
Let me know if you find anything more out.
Thanks in advance