I did mine on my 2005 ST3 this summer. It's not hard, just tedious removing all that stuff to get at it, wheel, rear brake, hugger, shock, link arm, shifter pedal assembly, the whole exhaust system. The only "tricky" part is to pay attention how the shims come out. There are shims on both sides but any extra shims go on one particular side to keep the chain aligned with the counter shaft and rear sprocket. Pay attention when they come out and replace them the same way, the extra shim(s) are supposed to go on the right side, but mine came out with the extra shims on the left side as opposed to the right so that's how I refitted them. There's a certain amount of axial clearance/play, 0.1 mm, as per the manual: "when a .010 mm feeler gauge or shim is hard to fit there is no need to shim the shaft." The axle is held in place on both sides by circlips. They are spring steel so be careful you don't launch them when you pull them out. I think I had to remove 2 of the center stands mounting bolts, not the one that goes through the engine, to get at the pinch bolts which are just plain bolts. Good luck.