My G11 is for sale but I wanted to keep the Stelvio shock and replace it with the stock item. Originally the shock was changed while the swingarm was off for lubrication, but I knew how to do it the easy way so I am sharing that with you.
The bike:

Stelvio shock in place:

Battery out, airbox access open:

Pretty clean in there, this is a bike with only 10K on the clock:

I pulled the snorkels off the F.I. and unplugged or unclipped any fuses, wires or hoses that got in my way. Only a couple of each. Once done I could tip the airbox up without actually removing it to expose the top of the shock.

Unbolt the shock from the bottom first, then undo the top and it comes right out. The Stelvio item actually fit better! Assembly is the reverse of disassembly except you do up the bottom of the shock first and then lift the tire and swingarm to locate the top of the shock. Make sure all your snorkels, hoses, fuses and wires are in place and button it back up. I estimate an hour if you know what you are doing. It took me two...