{"product_id":"ap-exhaust-644178-catalytic-converter-front","title":"AP Exhaust 644178 Catalytic Converter - Front","description":"\u003ch2\u003eOverview\u003c\/h2\u003e\u003cp\u003eAP Exhaust 644178 is a Federal \/ EPA direct-fit catalytic converter built for BMW applications that require exact OE dimensions and fitment. It uses stainless steel construction, a welded V-band inlet flange, and two O2 sensor ports for a clean replacement setup.\u003c\/p\u003e\u003cp\u003eCompatible with BMW 535i, 535i xDrive, 640i, 740i, 740Li, 740Li xDrive, X5, and X6 front applications, this converter is engineered for direct installation on the listed vehicles. AP Exhaust 644178 is also cross-referenced to 18407645241 for the same application.\u003c\/p\u003e\u003ch2\u003eKey Features\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eFederal \/ EPA direct-fit catalytic converter\u003c\/li\u003e\n\u003cli\u003eStainless steel body for exhaust system durability\u003c\/li\u003e\n\u003cli\u003eWelded V-band flange inlet for OE-style connection\u003c\/li\u003e\n\u003cli\u003eTwo O2 sensor ports for sensor integration\u003c\/li\u003e\n\u003cli\u003eBuilt to exact OE dimensions and fitment\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eDetailed Description\u003c\/h2\u003e\u003cp\u003eAP Exhaust 644178 is part of the Direct Fit Converter line, a product line focused on OE-style replacement fitment and manufacturing consistency. The converter uses ARISTO substrate chemistry and advanced production methods to support efficient converter loading while maintaining the dimensional accuracy needed for proper installation. For BMW 535i, BMW 640i, and BMW X5 front applications, this design helps match the original exhaust layout without custom fabrication.\u003c\/p\u003e\u003cp\u003eThe stainless steel body, 19-inch overall length, and 3.12-inch OD outlet reflect a direct-fit configuration intended for the listed BMW models. AP Exhaust 644178 is a practical replacement choice when the original catalytic converter is restricted, damaged, or no longer performing as required.\u003c\/p\u003e\u003ch2\u003eWhat It Is Used For\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eReplacing a failed or inefficient catalytic converter\u003c\/li\u003e\n\u003cli\u003eRestoring exhaust flow after converter restriction\u003c\/li\u003e\n\u003cli\u003eAddressing emissions-related drivability concerns\u003c\/li\u003e\n\u003cli\u003eReplacing a damaged OE-style exhaust component\u003c\/li\u003e\n\u003cli\u003eMaintaining proper sensor placement with two O2 ports\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\u003cp\u003eFits 2011-2016 BMW 535i, front; 2011-2016 BMW 535i xDrive, front; 2012-2015 BMW 640i, front; 2013-2015 BMW 740i, front; 2013-2015 BMW 740Li, front; 2013-2015 BMW 740Li xDrive, front; 2011-2014 BMW X6, front; and 2011-2013 BMW X5, front. Review the emissions notes before ordering, as some applications are listed for Federal and California emissions and include state-use restrictions. Verify flange style, sensor port count, and outlet dimensions against the original part before installation.\u003c\/p\u003e\u003ch2\u003eQuality Assurance\u003c\/h2\u003e\u003cp\u003eAP Exhaust states that its manufacturing process uses automated workstations, spinner welding equipment, and high-speed production lines to maintain OE dimensions and fitment consistency. The Direct Fit Converter line is built around replacement accuracy and controlled production standards.\u003c\/p\u003e","brand":"AP Exhaust","offers":[{"title":"Default Title","offer_id":53503736873141,"sku":"BBDL-644178","price":594.36,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0628\/1442\/1173\/files\/AP_644178_Top.jpg?v=1791616232","url":"https:\/\/www.partcatalog.com\/products\/ap-exhaust-644178-catalytic-converter-front","provider":"PartCatalog","version":"1.0","type":"link"}