Mini Factory 4.1 Slip-On MufflerFactory 4.1 muffler available in natural titanium or blue anodized titanium with titanium end capsThe lightest mufflers availableSuperior power and performance - horsepower improved throughout the rpm rangeFeature exclusive proprietary Chamber Core technologyFactory Forward Engineering centralizes mass, improves handlingMade from premium quality American materialsCustomize with performance tuning inserts and spark arrestor moduleMeet AMA sound requirements on most models; inserts available for others