Whether your 2011 GMC Sierra 2500 HD needs more power, a direct-fit exhaust replacement, or an EPA/CARB-compliant catalytic converter, MagnaFlow and BRExhaust use the best components and state-of-the-art manufacturing to deliver the performance and longevity you can count on. MagnaFlow builds its Performance Exhaust Systems with mandrel-bent stainless steel to improve flow and produce a deeper, more aggressive exhaust note on your Sierra 2500 HD. For a factory-spec replacement, BRExhaust Replacement Exhaust Systems, part of the MagnaFlow Group, deliver OE form, fit, and function in a single kit for straightforward installation. If your 2011 Sierra 2500 HD needs a catalytic converter, MagnaFlow engineers its OEM-grade converters with precise catalyst loading to meet or exceed EPA and CARB standards and keep your Check Engine Light off. Every exhaust system and direct-fit converter ships complete with all parts, gaskets, and hardware; no fabrication required. Select your 2011 GMC Sierra 2500 HD sub-model and engine size to find the right part; for catalytic converters, confirm your state of vehicle registration to ensure full compliance.