http://www.classicchambered.com/
Not quite glasspacks but BETTER... less of the "popping" machine-gun-like sound and more similar to flowmaster-type mufflers but still a very unique sound. I have the longest 2.5" ones on my Duster and they sounded great with the tired 318 before, should be almost tank-like when the 360 Magnum goes in LOL. Not to mention they are HANDMADE (and still ~$70 a muffler!) and the guy who makes them knows his stuff...