{"product_id":"black-3-downpipe-exhaust-for-2011-2016-lml-6-6l-duramax-diesel-chevrolet-gmc-2500hd-3500hd","title":"Black 3'' Downpipe Exhaust For 2011-2016 LML 6.6L Duramax Diesel Chevrolet GMC 2500HD 3500HD","description":"\u003cp\u003e---tab Description---\u003cstrong\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003ch3\u003eWhat Does a Downpipe Do?\u003c\/h3\u003e\n\u003cp\u003eThe stock downpipe on your 6.6L LML Duramax creates severe exhaust restriction, causing backpressure, turbo lag and high EGTs. Our 3-inch high-flow catless downpipe replaces the restrictive factory unit, optimizing exhaust gas flow, speeding up turbo spool, lowering operating temperatures, and unlocking reliable performance gains for daily driving and heavy towing.\u003c\/p\u003e\n\u003ch2\u003eProduct Specifications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine\u003c\/strong\u003e: GM Duramax 6.6L LML Turbo-Diesel 2015.5-2016\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePipe Diameter\u003c\/strong\u003e: 3 inch\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial\u003c\/strong\u003e: Stainless Steel\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSurface\u003c\/strong\u003e: Mirror Polish\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConfiguration\u003c\/strong\u003e: Catless\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFlange Type\u003c\/strong\u003e: Bolt-on (4-Bolt) with O2 sensor bung\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight\u003c\/strong\u003e: 2.32 kg (2320 g)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eLarger internal diameter than stock for dramatically increased exhaust flow\u003c\/li\u003e\n\u003cli\u003eTIG-welded stainless steel construction with mirror polish\u003c\/li\u003e\n\u003cli\u003eReduces turbo lag and enhances throttle response\u003c\/li\u003e\n\u003cli\u003eO2 sensor bung included for sensor retention\u003c\/li\u003e\n\u003cli\u003eDirect bolt-on to the factory turbocharger\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003csection\u003e\n\u003cp\u003eThis \u003cstrong\u003eCatless GM Duramax 6.6L LML Diesel (V8 Turbo-Diesel) downpipe\u003c\/strong\u003e replaces the restrictive factory downpipes and removes the catalytic converter for maximum flow. Engineered for Chevrolet \/ GMC, it’s a direct bolt-on upgrade that delivers lower EGTs, sharper turbo response, and increased flow.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003ch2\u003eWhat's Included\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eDownpipe\u003c\/li\u003e\n\u003cli\u003eGasket(s)\u003c\/li\u003e\n\u003cli\u003eO2 sensor bung\u003c\/li\u003e\n\u003cli\u003eMounting hardware\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eCheck Before Choosing\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCab \u0026amp; Chassis exclusion\u003c\/strong\u003e: Will NOT fit Cab \u0026amp; Chassis trucks — only fits pickup models (2500\/3500HD).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTune required for delete\u003c\/strong\u003e: Yes — a diesel tune (EFI Live \/ HP Tuners) is required to clear the CEL\/DPF codes and safely manage the increased flow on the LML.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStreet legality\u003c\/strong\u003e: No — not CARB or EPA certified. Off-road \/ competition use only.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEGT effect\u003c\/strong\u003e: Lowers exhaust gas temperatures under sustained load — a key benefit for towing and hard driving.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e---tab Fitment---\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e2015-2016 Chevy Silverado \/ GMC Sierra 2500HD \u0026amp; 3500HD 6.6L LML Duramax Diesel\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e---tab Installation Guide \u0026amp; FAQ---\u003c\/p\u003e\n\u003ch2\u003eInstallation Guide\u003c\/h2\u003e\n\u003ch3\u003ePre-Installation Checklist\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eConfirm your engine code and model year match the fitment list above\u003c\/li\u003e\n\u003cli\u003eNew gaskets and mounting hardware ready\u003c\/li\u003e\n\u003cli\u003e22mm slotted O2 sensor socket + PB Blaster on hand\u003c\/li\u003e\n\u003cli\u003ea diesel tune (EFI Live \/ HP Tuners) to clear CEL and DPF codes\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation Steps\u003c\/h3\u003e\n\u003col\u003e\n\u003cli\u003eLift the vehicle and secure it on jack stands\u003c\/li\u003e\n\u003cli\u003eSoak the O2 sensors and flange bolts with PB Blaster for 30+ minutes\u003c\/li\u003e\n\u003cli\u003eUnplug and remove the O2 sensors with the slotted socket\u003c\/li\u003e\n\u003cli\u003eRemove the factory downpipe and discard the old gasket\u003c\/li\u003e\n\u003cli\u003eBolt on the new downpipe with a fresh gasket\u003c\/li\u003e\n\u003cli\u003eReinstall and reconnect the O2 sensors\u003c\/li\u003e\n\u003cli\u003eFlash your tune to suppress the check engine light\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003ch3\u003eInstallation Notes\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eNever reuse the old gasket — it will cause an exhaust leak\u003c\/li\u003e\n\u003cli\u003eUse a slotted O2 socket, not a wrench — the sensor threads strip easily\u003c\/li\u003e\n\u003cli\u003eA catless downpipe triggers a CEL until the ECU is tuned\u003c\/li\u003e\n\u003cli\u003eExpect a stronger raw exhaust smell (normal for catless)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eFAQ\u003c\/h2\u003e\n\u003ch3\u003eDoes it fit Cab \u0026amp; Chassis trucks?\u003c\/h3\u003e\n\u003cp\u003eNo — this SKU is for pickup models only. Cab \u0026amp; Chassis requires a different SKU.\u003c\/p\u003e\n\u003ch3\u003eDo I need a tune on the LML?\u003c\/h3\u003e\n\u003cp\u003eYes — a diesel tune is required to clear the CEL\/DPF codes and safely manage increased flow.\u003c\/p\u003e\n\u003ch3\u003eWill it lower my EGTs?\u003c\/h3\u003e\n\u003cp\u003eYes — reducing back-pressure lowers exhaust gas temperatures under load, which is a key benefit for towing.\u003c\/p\u003e\n\u003ch3\u003eIs it street-legal?\u003c\/h3\u003e\n\u003cp\u003eNo — not CARB or EPA certified. Off-road \/ competition use only.\u003c\/p\u003e\n\u003cp\u003e---tab Shipping \u0026amp; Returns---\u003c\/p\u003e","brand":"SPELAB","offers":[{"title":"2015.5-2016 Black","offer_id":49343317770491,"sku":"SPES08391BK","price":159.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0174\/0609\/9556\/files\/3_DownpipeExhaustFor2011-2016LML6.6LDuramaxDieselSPELAB_3_301e0aac-25f6-4cd3-beb5-37e7211def28.webp?v=1774887285","url":"https:\/\/www.spelabautoparts.com\/products\/black-3-downpipe-exhaust-for-2011-2016-lml-6-6l-duramax-diesel-chevrolet-gmc-2500hd-3500hd","provider":"SPELAB","version":"1.0","type":"link"}