Vehicle fitment: 2011,2012,2013,2014 & 2015 Chevy / GMC Duramax Diesel LML. Silverado and Sierra pickup trucks. Crew cab short bed & crew cab long bed. This will not fit the 3500/4500/5500 Cab & Chassis commercial style truck. 2015 or 2015.5? 2015 is a split year. The 2011-2015 downpipe is secured to the turbo-direct pipe using a V-band style clamp. The 2015.5-2016 uses a 3 bolt flange style connection. Be sure to visually verify the clamp style your truck is equipped with. Exhaust Material: T-409 stainless steel. Unlike T-304 Stainless its still magnetic. So if your testing to see if you actually got stainless; beware that a magnet will still stick to it. Thickness: 2mm Inlet Diameter: 4.0" What is the DPF and is it worth doing a DPF Delete? Most post-2007 diesel vehicles are fitted with a Diesel Particulate Filter (DPF) for emissions reasons, however there are a few disadvantages to this device; including constant maintenance and repairs. Because the DPF clogs up, it increases backpressure. Due to this pressure, the fuel flow is hugely disturbed and slowed down. Therefore, when you remove this filter, the fuel flows much easily and faster, increasing the overall fuel mileage.