[Formulajones]

Like money pits mentioned, there are garden variety turbo mufflers that are much like you described.
Dynomax is a bit of a different breed and known for their excellent flow characteristics while providing good sound that isn't overly loud. Most of their designs that I'm familiar with are a straight through design and use a packing material to dampen noise.
There are a few other mufflers that have copied the design and flow similar.