There is a thread here, called "Lowering the XSR900", that has some info.
Lowering the XSR900
If it is a leg length issue with touching the ground, I'd suggest checking into getting the seat lowered, that way you are not loosing any ground clearance.
And best way to find stuff on here, is to do a Google search like "fz09.org lower xsr900". I find doing a Google search works better than using the in forum search option.