{"product_id":"er-b58-downpipe","title":"Evolution Racewerks Competition Series 4.5\" Catless Downpipe — B58","description":"\u003cp\u003e\u003cstrong\u003eEvolution Racewerks 4.5\" Competition Series catless downpipe for the B58 inline-six.\u003c\/strong\u003e Three finish options. The B58 makes meaningfully more exhaust mass-flow than the B48 at the same boost level — 4.5\" is the size ER engineered specifically to match the B58's 4.5\" turbine housing outlet without creating a \"step\" transition that causes back-pressure.\u003c\/p\u003e\n\n\u003ch3\u003eWhy 4.5\" specifically\u003c\/h3\u003e\n\u003cp\u003eER's note from their own product page: \"The new turbochargers on the B58 engines utilize a much larger 4.5\" outlet compared to the 4\" outlet on the older N55 engines. If we ran a 4\" downpipe flange inlet so we can use 4\" tubing, a 'step' would be formed between the turbocharger outlet and downpipe inlet. Exhaust gas would hit this step and turbulence would form, causing back-pressure close to the turbocharger.\" ER had to source 4.5\" stainless tubing specifically — not commonly available — to keep the inlet seamless.\u003c\/p\u003e\n\n\u003ch3\u003eThree finish options\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eBrush Finish (standard):\u003c\/strong\u003e ER's default. Matte stainless appearance, ages cleanly under engine bay heat cycling.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003ePolish Finish:\u003c\/strong\u003e mirror-polished stainless. Shows in the engine bay; preferred by show-build customers.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSwainTech White Lightning:\u003c\/strong\u003e our signature white ceramic thermal coating — details below.\u003c\/p\u003e\n\n\u003ch3\u003eCatless reality\u003c\/h3\u003e\n\u003cp\u003eAll three finish variants are catless construction (no catalytic material). Race use only. Triggers CEL on stock calibration — Esse Werks Stage 2 \/ 3 calibrations clear rear O2 monitoring. The catted variant from ER's catalog is a separate ER product (the Sports Series 4\" catted, which uses 4\" tubing rather than 4.5\") — contact us for catted B58 sourcing.\u003c\/p\u003e\n\n\u003ch3\u003eWhat Evolution Racewerks builds in\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e100% 304-grade stainless steel construction\u003c\/li\u003e\n  \u003cli\u003eMandrel-bent piping — smooth transitions, no flow restrictions at the bends\u003c\/li\u003e\n  \u003cli\u003e100% TIG-welded by ER's in-house fabricators\u003c\/li\u003e\n  \u003cli\u003ePrecision CNC-machined flanges (billet 304 stainless)\u003c\/li\u003e\n  \u003cli\u003eMade in the USA — manufactured in-house at ER's California facility\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLimited Lifetime Warranty\u003c\/strong\u003e against manufacturing defects\u003c\/li\u003e\n  \u003cli\u003eFree shipping in the continental US on orders over $100 from Evolution Racewerks (we pass that through — no shipping markup from us)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eEGT bung included — standard on every Esse Werks ER order\u003c\/h3\u003e\n\u003cp\u003eEvolution Racewerks offers the EGT (Exhaust Gas Temperature) sensor bung as an optional add-on on their direct catalog. \u003cstrong\u003eWe include it on every ER downpipe \/ mid pipe we ship — no upcharge.\u003c\/strong\u003e Comes pre-installed with a 1\/8\" NPT plug so you don't need to run the EGT sensor immediately. When you're ready to add EGT monitoring to your build (recommended at Stage 2 and above for any sustained-load driving), the bung is already there.\u003c\/p\u003e\n\n\u003ch3\u003eSwainTech White Lightning — our signature coating\u003c\/h3\u003e\n\u003cp\u003eWhen we coat a part, we use one coating: SwainTech White Lightning — a true ceramic thermal barrier applied about 0.015\" thick (versus roughly 0.002\" for paint-style \"ceramic\" finishes) and sprayed molten so it bonds to the metal instead of sitting on top. It cuts radiant heat off the exhaust by roughly 35–55%, dropping underhood and intake temperatures, and keeps heat inside the pipe where it sustains exhaust velocity and scavenging. And it's white — a deliberate signature in a market that otherwise all looks the same in black. Select it above.\u003c\/p\u003e\n\n\u003ch3\u003eCalifornia restriction\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eThis product is not for sale, installation, or use on licensed vehicles in the State of California.\u003c\/strong\u003e 49-state product. Vehicle Compliance Waiver signed at order intake. International orders ship without restriction.\u003c\/p\u003e\n\n\u003ch3\u003eInstall\u003c\/h3\u003e\n\u003cp\u003e~3-4 hours at a competent shop. Reuses OEM hardware where applicable. Includes all hardware for complete installation.\u003c\/p\u003e\n\n\u003ch3\u003eFitment\u003c\/h3\u003e\n\u003cp\u003eAll B58 BMW applications — M240i, M340i (incl. Touring), M440i, Z4 M40i, X3 M40i, X4 M40i, X5 40i, X6 40i, X7 40i, 540i (incl. Touring), 740i, 840i, plus legacy F-chassis M235i (B58), 340i, 440i.\u003c\/p\u003e\n\u003cp\u003eThis part is the downpipe-side Core of every B58 Stage 2 build. The \u003ca href=\"\/products\/stage-2-kit-b58\"\u003eStage 2 Kit — B58\u003c\/a\u003e packages the matched parts + calibration for 8% under à la carte.\u003c\/p\u003e","brand":"Evolution Racewerks","offers":[{"title":"Brush Finish","offer_id":43280677699645,"sku":"EW-EXH-ER-B58-BRUSH","price":675.0,"currency_code":"USD","in_stock":true},{"title":"Polish Finish","offer_id":43280677732413,"sku":"EW-EXH-ER-B58-POLISH","price":725.0,"currency_code":"USD","in_stock":true},{"title":"SwainTech White Lightning","offer_id":43280677765181,"sku":"EW-EXH-ER-B58-CERAMIC","price":925.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0658\/2553\/8109\/files\/er-b58-downpipe-01.webp?v=1781743118","url":"https:\/\/essewerks.com\/products\/er-b58-downpipe","provider":"Esse Werks","version":"1.0","type":"link"}