Cobra PowrPro HP 2-Into-1 RPT Exhaust For Harley Dyna The PowrPro 2-into-1 system will increase power and torque far more than what your stock system is capable of doing. The system is equipped with a 4-inch muffler body that creates a rumble to be heard from miles. Features: Increases power and torque 4 muffler body Machined aluminum RPT tip in matte black Distinguished rumble expected of the H-D V-Twin power plant Equipped with a 222 heat shield Guaranteed to not undergo discoloration for the life of the product