{"title":"3500\/3700 Performance Series","description":"\u003cp\u003eBuilt specifically for the GM Vortec 3500\/3700 inline-five platform, this Performance Series brings custom fabrication quality to a growing community of enthusiasts. Every manifold, flange, and hardware kit is designed and tested fit in-house for perfect fit, strength, and performance. Whether you’re boosting, swapping, or refining your 3500\/3700 setup, these parts deliver precision-engineered results backed by real-world experience.\u003c\/p\u003e","products":[{"product_id":"gm-3-5l-vortec-3500-manifold-flange-304-ss","title":"GM 3.5L Vortec 3500\/3700 Manifold Flange (304 SS)","description":"\u003ch3 data-end=\"502\" data-start=\"187\"\u003e\u003cspan style=\"color: #ff2a00;\"\u003eNOW AVAILABLE! Limited supply! \u003c\/span\u003e\u003c\/h3\u003e\n\u003cp data-start=\"187\" data-end=\"502\"\u003e \u003c\/p\u003e\n\u003cp data-start=\"187\" data-end=\"502\"\u003eBuilding a turbo setup or custom header for the GM Atlas 3500\/3700 inline-5 (3.5L platform) starts with a solid flange. This is a raw, weld-ready exhaust manifold flange cut from 1\/2\" thick 304 stainless steel and left in a mill finish so you can port, match, and surface it exactly how your build needs.\u003c\/p\u003e\n\u003chr data-start=\"504\" data-end=\"507\"\u003e\n\u003ch2 data-start=\"509\" data-end=\"520\"\u003eFeatures\u003c\/h2\u003e\n\u003cul data-start=\"521\" data-end=\"910\"\u003e\n\u003cli data-start=\"521\" data-end=\"599\"\u003e\n\u003cp data-start=\"523\" data-end=\"599\"\u003e\u003cstrong data-start=\"523\" data-end=\"539\"\u003eApplication:\u003c\/strong\u003e GM Atlas 3500\/3700 Inline-5 (3.5L) exhaust\/manifold builds\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"600\" data-end=\"641\"\u003e\n\u003cp data-start=\"602\" data-end=\"641\"\u003e\u003cstrong data-start=\"602\" data-end=\"615\"\u003eMaterial:\u003c\/strong\u003e 304 stainless steel\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"642\" data-end=\"679\"\u003e\n\u003cp data-start=\"644\" data-end=\"679\"\u003e\u003cstrong data-start=\"644\" data-end=\"658\"\u003eThickness:\u003c\/strong\u003e 1\/2\" (12.7 mm)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"680\" data-end=\"726\"\u003e\n\u003cp data-start=\"682\" data-end=\"726\"\u003e\u003cstrong data-start=\"682\" data-end=\"693\"\u003eFinish:\u003c\/strong\u003e Raw mill finish (uncoated)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"727\" data-end=\"771\"\u003e\n\u003cp data-start=\"729\" data-end=\"771\"\u003e\u003cstrong data-start=\"729\" data-end=\"745\"\u003eCut Process:\u003c\/strong\u003e Precision laser cut\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"772\" data-end=\"850\"\u003e\n\u003cp data-start=\"774\" data-end=\"850\"\u003e\u003cstrong data-start=\"774\" data-end=\"788\"\u003eUse Cases:\u003c\/strong\u003e Turbo manifolds, NA headers, custom downpipes, fab projects\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"851\" data-end=\"910\"\u003e\n\u003cp data-start=\"853\" data-end=\"910\"\u003e\u003cstrong data-start=\"853\" data-end=\"868\"\u003eWeld-Ready:\u003c\/strong\u003e Ideal for TIG\/MIG stainless fabrication\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"912\" data-end=\"915\"\u003e\n\u003ch2 data-start=\"917\" data-end=\"938\"\u003eWhy 304 Stainless?\u003c\/h2\u003e\n\u003cp data-start=\"940\" data-end=\"991\"\u003e304 is a proven exhaust material because it offers:\u003c\/p\u003e\n\u003cul data-start=\"993\" data-end=\"1190\"\u003e\n\u003cli data-start=\"993\" data-end=\"1059\"\u003e\n\u003cp data-start=\"995\" data-end=\"1059\"\u003e\u003cstrong data-start=\"995\" data-end=\"1026\"\u003eStrong corrosion resistance\u003c\/strong\u003e for street and performance use\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1060\" data-end=\"1124\"\u003e\n\u003cp data-start=\"1062\" data-end=\"1124\"\u003e\u003cstrong data-start=\"1062\" data-end=\"1091\"\u003eGood high-temp durability\u003c\/strong\u003e for manifolds and turbo setups\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1125\" data-end=\"1190\"\u003e\n\u003cp data-start=\"1127\" data-end=\"1190\"\u003e\u003cstrong data-start=\"1127\" data-end=\"1152\"\u003eExcellent weldability\u003c\/strong\u003e with common stainless filler metals\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"1192\" data-end=\"1195\"\u003e\n\u003ch2 data-start=\"1197\" data-end=\"1240\"\u003eImportant Note on Flatness (Please Read)\u003c\/h2\u003e\n\u003cp data-start=\"1242\" data-end=\"1447\"\u003eThese flanges \u003cstrong data-start=\"1256\" data-end=\"1293\"\u003edo arrive with a slight bow\/warp.\u003c\/strong\u003e\u003cbr data-start=\"1293\" data-end=\"1296\"\u003eThat’s normal for \u003cstrong data-start=\"1314\" data-end=\"1342\"\u003elaser-cut 1\/2\" stainless\u003c\/strong\u003e — the cutting heat can introduce mild movement. This is common across the industry and \u003cstrong data-start=\"1430\" data-end=\"1447\"\u003enot a defect.\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp data-start=\"1449\" data-end=\"1552\"\u003eAfter welding, flanges should be surfaced flat to guarantee sealing. We recommend one of the following:\u003c\/p\u003e\n\u003cul data-start=\"1554\" data-end=\"1672\"\u003e\n\u003cli data-start=\"1554\" data-end=\"1605\"\u003e\n\u003cp data-start=\"1556\" data-end=\"1605\"\u003e\u003cstrong data-start=\"1556\" data-end=\"1575\"\u003eBlock sand flat\u003c\/strong\u003e on a known-flat surface, or\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1606\" data-end=\"1672\"\u003e\n\u003cp data-start=\"1608\" data-end=\"1672\"\u003e\u003cstrong data-start=\"1608\" data-end=\"1630\"\u003eMachine\/plane flat\u003c\/strong\u003e (best for high-boost or high-heat builds)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"1674\" data-end=\"1791\"\u003eWelding heat can add a bit more movement, so \u003cstrong data-start=\"1719\" data-end=\"1759\"\u003efinal surfacing is standard practice\u003c\/strong\u003e on performance manifold builds.\u003c\/p\u003e","brand":"Foreverfabrication","offers":[{"title":"Default Title","offer_id":46013334028477,"sku":"FF-AT-35-MF-SS50","price":100.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1254\/5501\/files\/3700_Header_flange_2.png?v=1765733426"},{"product_id":"vortec-3500-turbo-manifold","title":"Vortec 3500\/3700 Turbo Manifold","description":"\u003cp data-start=\"293\" data-end=\"616\" class=\"\"\u003e\u003cstrong\u003e\u003cspan style=\"color: rgb(255, 42, 0);\"\u003eNOW IN STOCK! LIMITED SUPPLY!\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp data-start=\"293\" data-end=\"616\" class=\"\"\u003eOur new turbo manifold for the Vortec 3500\/3700 inline-5 is engineered for high-performance applications. Built using Schedule 10 stainless steel cast piping, this manifold delivers maximum durability and flow...well the flow that a log manifold can. Every unit is TIG-welded and back-purged for strength, performance, and reliability.\u003c\/p\u003e\n\u003cp data-start=\"618\" data-end=\"692\" class=\"\"\u003e📸 The turbo shown in the photos is a VSR 67\/66 Billet from VS Racing.\u003c\/p\u003e\n\u003chr data-start=\"694\" data-end=\"697\" class=\"\"\u003e\n\u003ch3 data-start=\"699\" data-end=\"723\" class=\"\"\u003e🔧 Manifold Details:\u003c\/h3\u003e\n\u003cul data-start=\"724\" data-end=\"1042\"\u003e\n\u003cli data-start=\"724\" data-end=\"789\" class=\"\"\u003e\n\u003cp data-start=\"726\" data-end=\"789\" class=\"\"\u003eDesigned specifically for turbocharged Vortec 3700 setups\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"790\" data-end=\"863\" class=\"\"\u003e\n\u003cp data-start=\"792\" data-end=\"863\" class=\"\"\u003eBuilt from Schedule 10 stainless steel for exceptional durability\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"864\" data-end=\"940\" class=\"\"\u003e\n\u003cp data-start=\"866\" data-end=\"940\" class=\"\"\u003eTIG welded and back-purged for superior weld quality and performance\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"941\" data-end=\"975\" class=\"\"\u003e\n\u003cp data-start=\"943\" data-end=\"975\" class=\"\"\u003eProduct is currently made to order, but we plan to batch order if popular \u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"976\" data-end=\"1042\" class=\"\"\u003e\n\u003cp data-start=\"978\" data-end=\"1042\" class=\"\"\u003eOrders will be fulfilled on a first-come, first-served basis\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"1044\" data-end=\"1047\" class=\"\"\u003e\n\u003ch3 data-start=\"1049\" data-end=\"1079\" class=\"\"\u003e🛠️ Wastegate Integration:\u003c\/h3\u003e\n\u003cp data-start=\"1080\" data-end=\"1255\" class=\"\"\u003eWant external boost control? We offer the option to pre-weld a wastegate pipe and flange to your manifold before shipping. We're currently set up for the following wastegates:\u003c\/p\u003e\n\u003cul data-start=\"1257\" data-end=\"1355\"\u003e\n\u003cli data-start=\"1257\" data-end=\"1297\" class=\"\"\u003e\n\u003cp data-start=\"1259\" data-end=\"1297\" class=\"\"\u003e🔹 \u003cstrong data-start=\"1262\" data-end=\"1279\"\u003eTiAL MVR 44mm\u003c\/strong\u003e (V-band flange)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1298\" data-end=\"1355\" class=\"\"\u003e\n\u003cp data-start=\"1300\" data-end=\"1355\" class=\"\"\u003e🔹 \u003cstrong data-start=\"1303\" data-end=\"1337\"\u003eTurbosmart GenV HyperGate 45mm\u003c\/strong\u003e (V-band flange)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eBoth Tial 44mm \u0026amp; Turbosmart 45mm flanges are the same!\u003c\/strong\u003e\u003c\/p\u003e\n\u003chr data-start=\"1480\" data-end=\"1483\" class=\"\"\u003e\n\u003ch3 data-start=\"1485\" data-end=\"1509\" class=\"\"\u003e⚠️ Important Notice:\u003c\/h3\u003e\n\u003cp data-start=\"1510\" data-end=\"1798\" class=\"\"\u003eThis product is intended for \u003cstrong data-start=\"1539\" data-end=\"1576\"\u003eoff-road and motorsports use only\u003c\/strong\u003e. It is not CARB-compliant and is \u003cstrong data-start=\"1610\" data-end=\"1623\"\u003enot legal\u003c\/strong\u003e for use on emissions-controlled vehicles in California or other states following CARB regulations. By purchasing, you confirm that this product is for race\/off-road use only.\u003c\/p\u003e\n\u003chr data-start=\"1800\" data-end=\"1803\" class=\"\"\u003e\n\u003ch3 data-end=\"240\" data-start=\"222\"\u003e📦 Order Info:\u003c\/h3\u003e\n\u003cul data-spread=\"false\"\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cspan\u003e\u003cstrong\u003eEstimated ship start\u003c\/strong\u003e\u003c\/span\u003e\u003cspan\u003e: end of April-Early June 2026\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cspan\u003e\u003c\/span\u003e\u003cspan style=\"font-size: 0.875rem;\"\u003eOrders are shipped in the order received. You’ll get tracking via email as soon as your unit leaves the shop.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-end=\"1402\" data-start=\"1399\"\u003e\n\u003ch3 data-start=\"1404\" data-end=\"1431\"\u003e🔁 Return Policy:\u003c\/h3\u003e\n\u003cp data-end=\"1322\" data-start=\"1270\"\u003eReturns are accepted within 30 days of delivery.\u003c\/p\u003e\n\u003cul data-end=\"1481\" data-start=\"1324\"\u003e\n\u003cli data-end=\"1377\" data-start=\"1324\"\u003e\n\u003cp data-end=\"1377\" data-start=\"1326\"\u003eA 10% restocking fee will apply to all returns.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-end=\"1418\" data-start=\"1378\"\u003e\n\u003cp data-end=\"1418\" data-start=\"1380\"\u003eShipping costs are non-refundable.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-end=\"1481\" data-start=\"1419\"\u003e\n\u003cp data-end=\"1481\" data-start=\"1421\"\u003eItems must be returned in unused, uninstalled condition.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-end=\"1729\" data-start=\"1483\"\u003eIf a product arrives with a manufacturing defect or workmanship issue, contact us immediately. We will make it right through repair, replacement, or refund at our discretion.\u003cbr data-end=\"1664\" data-start=\"1661\"\u003eAll manifolds are thoroughly quality-checked before shipment.\u003c\/p\u003e\n\u003cp data-end=\"1801\" data-start=\"1731\"\u003eTo initiate a return, please contact us before sending any items back.\u003c\/p\u003e","brand":"Foreverfabrication","offers":[{"title":"3.5L Log Manifold with NO wastegate piping","offer_id":46253323747517,"sku":"FF-AT-35-TM-NWG","price":750.0,"currency_code":"USD","in_stock":false},{"title":"3.5L Log Manifold w\/ welded Turbosmart\/tial wastegate flange","offer_id":46253323780285,"sku":"FF-AT-35-TM-WG","price":850.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1254\/5501\/files\/DJI_20251229_140313_019.jpg?v=1767115824"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1254\/5501\/collections\/IMG_8829.jpg?v=1769743063","url":"https:\/\/shop.foreverfabrication.com\/collections\/3500-performance-series.oembed","provider":"Foreverfabrication","version":"1.0","type":"link"}