Never saw one before but the idea of the discs on the back is to make it tunable.
When we did engine work to my Harley for drag racing they will recommend the
amount of discs to use by the work you have done to the engine.
The Supetrapp Exhaust systems are a good way to add horse power and
are much lighter than standard exhaust.
Can honestly say never new it to be an OEM with Kohler.