I bought a lowering kit for my 08 XTR from BikeFarm. It was I later found out it was the wrong one and lowered the bike too much. 43mm actually. I Got bar raisers and lowered the forks by 50mm (which equated to 43mm vertically).

All was well till the wife and I both got on it and turned the tap on full. We are both heavy and the rear tyre wore through the tool holder box. Also it snapped off the upper chain stay roller and the rear disc calliper cover broke on the exhaust.

I am not trying to put you off but if you go for the 3cm lowering kit that should be ok but do not overload the bike too much and if you do make sure the suspension is jacked up.

I also cut 25mm off the sidestand to accommodate it and cut some foam out of the saddle.

Good luck.

__________________
We are now retired....so....... lots of this and this and no more of this or this