i've been looking into this for the past week... from what i can tell ksport used a 50mm diamater strut, across the board same strut for every application which is chrome. some newer applications are getting a 52mm strut which is black but now they also make the 50mm in black now (front and rear are different so 4 total different struts not sure on the drift or rally stuff but that doesn't apply to us)
the black ones click when you adjust them the chrome ones do not (btw only like the first 7 or so out of the 32 settings acutally work)
since they use the same strut for everything the piston is the same size on everything.
http://forums.nicoclub.com/koni-8611-8610-project-t336836.html
once i saw how much of a pain in the ass this was i gave up the idea.
this is on a tein, much more straight foward
http://nissanroadracing.com/showthread.php?t=846