so by this time I have ridden more with the end cap in "fallen out position" than with it in, and it's driving me crazy!! I tried with loctite on the screw and it melted away, so I hose clamped a "Cola" can on the end and had to pie cut a section of it because the muffler is narrower than the can. within 5minutes of this addition it was tearing open and falling off the end, is the solution to put the cap on the muffler and then the can over it to hold it on. I'm thinkin the back pressure tore the can that proceeded to loosen and tear further so the cap would shield the slit in the can in the from the back pressure and the pressure would be distributed evenly instead of focusing on the slit. BTW its a black cat con muff from a year or two ago.