I did the conversion and it works great. Here's a link to what I posted on this site.Asearch using the words, 'Harley' and 'mufflers' netted the following http://www.goldwingfacts.com/forums/view_topic.php?id=590&forum_id=1&highlight=harley+mufflerscmeador,
One thing I haven't seen mentioned yet, is using a set of gl1000 headers, & a set of Harley mufflers. A lot of gl1100 owners are doing this. The NEW Harley mufflers can be had relatively cheap on eBay ($20-$50). One of the first things a new Harley owner does it take off the quiet stock mufflers (what the point of having a machine that fires on forty-five degrees if you can't hear it?:cheeky1. You would have to make a bracket for the muffle, but they look & sound nice.