My exhausts have been modded by butchering the last little bit of pipe and now looks like a removable db killer except the one thing it doesn't do is kill db's! Anyone taken their standard cans to bits that can post some pictures & dimensions of the little end pipes. It's been a long time since I played with 900ss cans and although I know that the pipe needs to be long enough to fit into the middle volume of the can I'm not sure whether it's a simple piece of pipe or has holes & what diameter it is.
Internals before butchery would look something like the pipes below. All removable baffles I've seen have been in addition and have similar "baffling" in the metal or are just a straight pipe. The end piece will have an outer dimension to fit the inner diameter of your end cap (and presumably a small hole for a securing screw). DB killers inserted into an empty can aren't going to do anything