{"product_id":"catalytic-converter-for-mercury-grand-marquis-2003-2011-4-6l-left-right","title":"Catalytic Converter for Mercury Grand Marquis (2003-2011) 4.6L Left \u0026 Right","description":"\u003ch2 style=\"font-size: clamp(18px, 3vw, 21px); margin-bottom: 15px; line-height: 1.3;\"\u003eDirect-Fit Left \u0026amp; Right Catalytic Converter Pair for 2003-2011 Mercury Grand Marquis (Panther Platform)\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat it Does:\u003c\/strong\u003e The Left \u0026amp; Right Catalytic Converter assembly replaces deteriorated stock catalytic converters on the 2003-2011 Mercury Grand Marquis to restore exhaust gas flow and eliminate P0420\/P0430 catalyst efficiency diagnostic trouble codes.\u003c\/p\u003e\n\n\u003ch3\u003eThe Stock Mercury Grand Marquis Substrate Degradation\u003c\/h3\u003e\n\u003cp\u003eFactory exhaust converters on the aging \u003cstrong\u003ePanther platform\u003c\/strong\u003e frequently suffer from washcoat depletion, thermal fracture, and cell clogging after decades of heat cycling. In vehicles equipped with the \u003cstrong\u003eModular 4.6L V8\u003c\/strong\u003e, oil blow-by and unburnt fuel gradually coat the original ceramic brick, inducing high exhaust backpressure. This bottleneck chokes scavenging dynamics, increases cylinder head temperatures, triggers continuous check engine lights, and robs the engine of factory mid-range torque.\u003c\/p\u003e\n\n\u003ch3\u003eThe Engineering Solution\u003c\/h3\u003e\n\u003cp\u003eThis direct-fit dual catalytic converter assembly is manufactured using high-grade stainless steel tubing for maximum corrosion resistance and structural rigidity. High-flow ceramic substrates provide dense noble-metal washcoat surface area for optimal hydrocarbon and carbon monoxide conversion efficiency without impeding exhaust velocity. Precision-machined, OE-spec laser-cut flanges mate directly to factory exhaust manifolds and intermediate pipes, retaining stock oxygen sensor locations for a weld-free bolt-on installation.\u003c\/p\u003e\n\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003cdiv style=\"overflow-x: auto; margin-bottom: 20px;\"\u003e\n  \u003ctable width=\"100%\" style=\"border-collapse: collapse; border: 1px solid #e0e0e0; font-size: 14px; min-width: 300px;\"\u003e\n    \u003ctr style=\"background-color: #f9f9f9;\"\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eFitment\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e2003-2011 Mercury Grand Marquis\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eEngine \/ Chassis\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003eModular 4.6L 2V \/ Panther Platform\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #f9f9f9;\"\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eStock Output\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e224–239 hp \/ 275–287 lb-ft\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eReplaces OEM Part #\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e642161, 642179, 54345, 54346, 30383, 30384\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch3\u003eCompatibility\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e2003-2011 Mercury Grand Marquis GS 4.6L V8\u003c\/li\u003e\n  \u003cli\u003e2003-2011 Mercury Grand Marquis LS 4.6L V8\u003c\/li\u003e\n  \u003cli\u003e2003-2005 Mercury Grand Marquis LSE 4.6L V8\u003c\/li\u003e\n  \u003cli\u003e2005 Mercury Grand Marquis Ultimate Edition 4.6L V8\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003ch4\u003eDoes this fit the Panther platform Grand Marquis?\u003c\/h4\u003e\n\u003cp\u003eYes, this is a direct fit for the 2003-2011 Mercury Grand Marquis equipped with the Modular 4.6L V8 engine.\u003c\/p\u003e\n\n\u003ch4\u003eIs this catalytic converter set EPA compliant?\u003c\/h4\u003e\n\u003cp\u003eYes, these converters comply with federal 48-state EPA standards, but they are not certified for sale or use in California or New York.\u003c\/p\u003e\n\n\u003ch3\u003eThe Mercury Road-Going Caliber\u003c\/h3\u003e\n\u003cp\u003eEngineered to handle long-distance highway cruising and heavy-duty V8 duty cycles, this dual converter assembly ensures your full-size sedan delivers clean tailpipe emissions, restored engine responsiveness, and dependable road service.\u003c\/p\u003e","brand":"VelocityMax","offers":[{"title":"Default Title","offer_id":67537737842936,"sku":"DS-EJUI2RD8Z","price":233.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0800\/1290\/2648\/files\/catalytic-converter-for-mercury-grand-marquis-2003-2011-4-6l-left-right-1.jpg?v=1790616492","url":"https:\/\/performancechiptuning.com\/products\/catalytic-converter-for-mercury-grand-marquis-2003-2011-4-6l-left-right","provider":"Performance Chip Tuning","version":"1.0","type":"link"}