I picked up a pair of the high-mount stailess rounds and they fit relatively well.
The rubber sleeves are for the springs.
i also bought the same ones for my 2001 600 and decided that i did not like the way it was mounted so i came up with my own way so it does not just clamp to the frame. I also decided that it was not much louder than my cored ones so i took them apart removed all the the packing wrapped the core with some header wrap, secured it with wire and put it back together and now it sounds amazing