Flowmaster 717885 Flow FX Cat-Back Exhaust for 2011-2018 GM Silverado/Sierra 1500 6.2L V8 Flow FX 3.5" Cat-BackThe new Flowmaster Flow FX cat back exhaust system for the 2011 2018 GM Silverado Sierra 1500 trucks with the 6. 2 Liter engine is manufactured using durable 409 stainless steel throughout and features 3. 5 inch mandrel bent pipes for better exhaust gas flow, and a Flow FX "straight through" muffler is used for a moderate sound level and maximum performance. Maximum increases on the dyno revealed +16 hp and +16 lb ft at the rear wheels. This system