Stop by your local bike shop and ask for some exhaust repack material. My shop sold me a pack of FMF (the dirt bike people) brand material for around $15. There's a thread here somewhere. I used "hardware screen" from Lowe's to wrap around the packing. Cut the screen to size, twist tie a few wires to hold it around the packing and slip it into the pipe. I had removed about 25% from my SS pipes when I bought them, but a check a few years later revealed most of that had eroded, leaving very little in the pipe (and that harsh top end sound got a little old). I'll try to dig up my old thread and/or pix.
