Hello,
Just saw your post, sorry for being so slow.
I bought a Hindle slip on for my 650s this past spring. To make it work on my bike I needed two parts from Hindle (and a recycled part from the stock muffler). I bought an Hindle Aluminum muffler along with the Hindle 650s elbow. I needed to re-use the gasket from the stock muffler I removed.
I bought the 'stealth' muffler as I was not looking to make myself deaf. I believe the sound is quite nice, is not too much that I annoy people but loud enough so that people do hear me now.
Let me know if you need any more info or pics.
ATG