Magnaflow XL Multi-Chamber Performance mufflers are designed with large diameter perforated tubes and baffles engineered especially to offer a reduced resonance and provide better horsepower. These mufflers feature calibrated tuning gate openings that allow the portion of waves to pass through, which are reflected from the muffler walls to cancel out the harsh sounds. The large-diameter core allows an easy flow of exhaust gases compared to a louvered style core and the careful balance between the perforation size and baffle tuning gates make this muffler great for performance.