I don't know about this particular fork but topout noise is usually due to worn-out or cracked top-out bumpers (a small elastomer bumper that cushions metal-on-metal contact). This would be the first suspect in my list of culprits to check (or have a shop check for).
It's going to be part no. 10 on this exploded view:
http://www.srsuntour-cycling.com/cus...=Exploded+view
Edit - - crap, link doesn't work that way. Click this:
http://www.srsuntour-cycling.com/SID...tail&tnid=1228
and select the Exploded View PDF.
BTW, your Suntour XCT 75 doesn't have damping - - only spring preload.