Sierra - Silverado Cat-Back Right Exits Model 2019 - 2026 Features and Specifications of BTM Cat-Back for GMC and Silverado: Comes with the cat-back, one factory exit + two right exits. Resonator size is 3 inches. Resonator valve thickness is 4 mm (thicker than usual valve thicknesses). Benefit: stronger resistance to throwing and cutting. BTM Cat-Back with the device (electronic) 3 inches. One-year warranty on welding. 304 Steel. Increases engine performance and horsepower. Compatible with Sierra and Silverado models from 2019 - 2026.