Aperture Science Technology (AST) product--sells new from manufacturer for $85 shipped. Used for about one year. You'll need heat tape. Price includes shipping. Feel free to ask questions!
Yes, it's available. The reason I removed it is due to decreasing my oil change intervals to 3K at the suggestion of my mechanic. Since sludging is unlikely under that regimen (including full synthetic, Honda filter, and BG EPR each time), the Muzzler isn't necessary.