The myth is that:
The lower spring perch, the one that is on the strut (NOT the one that is on the camber plate!!!) is located lower on the ZCP strut than on the normal one.
This was mentioned several times on the forum and never really confirmed!
I would only confirm that this lower perch is exactly at the same location for all struts, ZCP, non ZCP, 1M, EDC, Japan version. The ZCP lowering is done by shorter springs only.