I've tried this a couple of times now, and am having exactly ZERO success. Put the full Arrow exhaust on my Duke 690 last off season. Factory packing lasted approximately 4 days before it was painfully loud and started to discolor the Ti canister... which, as it turns out, is fantastically successful. These big bore motors must deliver one hell of a pressure wave. First repack was completed using fine steel window screen around the core, then generous amounts of fiberglass 4-stroke repacking material (mat), then another layer of window screen around that so it would slide back into the can. Some fresh RTV (which looked totally professional, I must say) and I was ready to go. That repack lasted approximately 4 track sessions before we were back to painfully loud and more discoloration. When I opened up the canister every bit of everything I had put inside was gone, except for a small amount of screen near the end cap. After doing some more research I changed strategies. Started with 2 layers of Copper mesh spiral wound around the core, then pleated some heavyweight Kevlar fabric and wrapped completely around the copper. A layer of 1" ceramic mat followed the Kevlar. All was kept tight with some safety wire to enable sliding the core back into the canister. More RTV. Optimism reigns. Nope. One 15 minute practice session and 2 8-laps races later we were back to loud and discolored. Here's what it looked like when I opened it up: At least some of the copper survived?! It was fantastically fast, but super loud. Anyone care to offer some no BS advice on what to do next? I'm not sure what to do.
http://areapnolimits.com/products/Muffler-Packing.php Pack the shit out of it I would put the sleeve back on the end closest to the engine and rivet it. Put the core in and pack around it. You need to pack it as much as you can. The first couple of inches closest to the engine are the most important. I also think there is a steel wool type of mesh that should go around the core before putting it in.
HMF used to sell the best muffler packing that worked phenomenal on big bore high RPM/turbo bikes. It was so good I used it to repack my Akra mufflers. Ive seen some folks use that header wrap around "bagged" packing on the perforated sleeve... then stuffed what they could into the void between the can & wrapped packing.
