Just wondering if there's some form of exhaust sealer or glue. I bought my pipes used and needed to re-cerakote them. Pulling off the endcaps and baffles, it appeared there was some black buildup or something inside the pipe that kept everything from moving (they were tough to get out too). They really only have 1 quarter inch bolt that holds them in and since re-inserting them there is a bit of play. Is there likely something that was used to help keep them in place or was I just looking at likely exhaust buildup along the endcap edges?

 

I have seen silicon with bolts to hold on an exhaust tip. Not saying for a fact that's your case but I have seen it done before.