Hooker engineers have integrated the latest in race header design into their Aero Chamber muffler. By utilizing the step principal (various transitions in cross-sectional area), they are able to manage the exhaust pressure waves of each cylinder to enhance combustion for more power. In fact, dyno tests with a 406 c.i. SB-Chevy have proven that Aero Chamber helped produce 5ft./lbs. more torque than 2-1/2'' open pipes! Constructed from aluminized and stainless steel for long life and excellent durability.