The system I bought came with the muffler. The muffler that it came with is a very generic muffler that's found all over ebay on different exhausts for different bikes. But yeah, check the diameter as it's either going to fit an aftermarket full exhaust, or the OEM diameter which is tiny.@Dreadwil bought this system from company ANODIZING, with 51mm O.D. (outer diameter).
If any of your decide to go with the Chinesium route, ensure the O.D. of the exhaust pipe outlet matches (or is within a few mm of) the I.D. (inner diameter) of the slip-on you purchase (if you buy the pipe and muffler separate).
Regarding the packing, I've noticed a tiny bit of packing coming out the end of my muffler. Sometimes when I take the silencer out it will carry with it some of the packing debris. I'm hoping this is remnants/excess from the manufacturing process but I have my doubts. I haven't noticed any change in sound or heat (yet).