Cycle Shack Slash Down Catalyst Muffler for Harley Davidson 2009-11 FLH, FLT Manufacturer Part No. MHC-350SD Improved performance and a traditional deep, throaty exhaust tone Less heat on the rider&rsquo;s right leg (since we put the catalyst back in the mufflers) and improved styling Cycle Shack&rsquo;s in. Dresser Duallies in. front cylinder head pipe is routed to the right side muffler, while the rear cylinder head pipe is routed to the left side muffler (via the cross-under pipe) This configuration helped improve performance and gives unique styling