Ya, a guy by the name of wingwing is working on one. You can find the thread on www.gl1800riders.com . The name of the thread is 'Turbo is in ....'. It's in the tech board. A search for 'wingwing turbo' should find it.
BTW, the posts in the forums on www.gl1800riders.com are in reverse chronological order. The latest post is at the top of the first page. If you want to read the thread from the beginning, go to the last past and read from the bottom up.