We fitted these wheels to a mate's 525. We think they are off a 2001 GSXR600. They are 3.5x17" front, 4.5x17" rear. Picked 'em up at a swap meet.
This is the arvo we first toyed with the idea. They are not a drop-on fit - there was a bit of machining involved, but none to the wheels themselves. It was only to the rear disc, sprocket carrier wheel spacers etc.
I think they look pretty good on there now. They were even the right colour. I still have to get some photos of the completed job.