Not that I can think of. I'll roll it around in my head and if something comes to mind I'll let you know. Those won't tone it down much though. I have used those for years on my bikes to make it look like I had mufflers to keep the man happy. They don't muffle much.
Maybe you could take a pair of those , since they are very inexpensive , and put a set of the cheap baffles in them like some of these.
http://www.jpcycles.com/search.aspx?search=baffles&store=All
