Sierra - Silverado BTM Catback from 2007-2018 Comes with the catback: stock tip + two right-side tips. The muffler size is 3 inches. Thicknes of the muffler valve is 4 mm (the thickest among usual valve thicknesses). Benefit: stronger resistance to throwing and cutting. BTM Catback with the electronic device, 3 inches. Increases engine performance and horsepower. Compatible with Sierra and Silverado models from 2007-2018. Open for offers, and the sale is easy.