Description
D&D 634Z-31B Fat Cat 2 into 1 Exhaust for 2018-Newer Harley M8 Softail Models
Will fit softails that have mid controls or forward controls
The D&D 634Z-31B Fat Cat system is designed especially for the Street Bob, Low RIder, Slim, Fat Bob, Deluxe, Sport Glide and Heritage Classic Milwaukee Eights. Does not fit Breakout or Fat Boy. See 638Z-31B for those two models.
The Fat Cat is a 2 into 1 stepped header system at 1 3/4″-1 7/8″-2 1/8″ at collector -2 1/2″ where the muffler goes to the header. The M8 Softail Fat Cat full system is equipped with heat shields, exhaust gaskets, bolt kit and baffle and has a 4″ muffler housing with a louvered baffle and back cut tip.
It also comes with both 18mm and 12mm O2 bungs so it can be used with an auto tune module such as the Thundermax Auto Tune. This system is also designed to increase low end torque and horsepower.







