{"product_id":"milltek-secondary-catalyst-bypass-bmw-4-series-g82-m4-comp-s58-3-0-turbo-na-row-non-opf-gpf-21","title":"Milltek Secondary Catalyst Bypass BMW 4 Series G82 M4 Comp S58 3.0 Turbo NA ROW Non-OPF\/GPF 21+","description":"\u003ch2\u003eMilltek Secondary Catalyst Bypass for BMW 3 Series G80 M3 \u0026amp; M3 Competition S58 3.0 Turbo (North American\/ROW Non-OPF\/GPF Cars Only) (2021 onwards) – Maximum Flow, Motorsport Use\u003c\/h2\u003e\n\u003cp\u003eThis is Milltek's large-bore downpipe and de-cat for the BMW 4 Series G82 M4 \u0026amp; M4 Competition S58 3.0 Turbo (North American\/ROW Non-OPF\/GPF Cars Only). It replaces the factory downpipe with a larger-bore pipe and removes the catalytic converter entirely, clearing the single most restrictive point in the exhaust for the biggest flow gain available at this position in the system. It's usually fitted alongside a Stage 2 remap, since the ECU needs to be told to expect the different readings the lambda sensors give once the cat's gone. It's offered in non-resonated or resonated versions, so you can pick the setup that suits how the car's used.\u003c\/p\u003e\n\u003cp\u003eIt's built for owners already committed to a serious power upgrade rather than a casual bolt-on, so pair it with the matching Milltek cat-back system for the full effect.\u003c\/p\u003e\n\u003cp\u003eBecause it removes the cat, it's intended for off-road and competition use. A de-catted car will fail an MOT emissions test and isn't legal to use on UK roads.\u003c\/p\u003e\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSystem Type:\u003c\/strong\u003e Secondary Catalyst Bypass\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEC Approved:\u003c\/strong\u003e No\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRace System:\u003c\/strong\u003e Yes\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eMade from T304L aircraft-grade stainless steel, which is anti-magnetic and resists discolouration\u003c\/li\u003e\n\u003cli\u003eMandrel-bent pipework keeps a constant diameter through every bend for unrestricted flow\u003c\/li\u003e\n\u003cli\u003eRemoves the factory catalyst for maximum flow (off-road and competition use only)\u003c\/li\u003e\n\u003cli\u003eResonated (quieter) or non-resonated (louder) versions\u003c\/li\u003e\n\u003cli\u003eDesigned, developed and manufactured in the UK by Milltek Sport\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFitment\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eBMW 3 Series G80 M3 \u0026amp; M3 Competition S58 3.0 Turbo (North American\/ROW Non-OPF\/GPF Cars Only) (2021 onwards)\u003c\/li\u003e\n\u003cli\u003eBMW 4 Series G82 M4 \u0026amp; M4 Competition S58 3.0 Turbo (North American\/ROW Non-OPF\/GPF Cars Only) (2021 onwards)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eNot suitable for:\u003c\/strong\u003e the BMW 3 Series F80 M3 \u0026amp; M3 Competition Saloon (Non OPF\/GPF Models Only), which needs the \u003ca href=\"\/products\/milltek-decat-downpipe-bmw-3-series-f80-m3-comp-saloon-non-opf-gpf-14-18\"\u003eMilltek Downpipe \u0026amp; De-cat BMW 3 Series F80 M3 \u0026amp; M3 Comp Saloon Non OPF\/GPF 14-18\u003c\/a\u003e; the BMW 3 Series F30 328i M Sport Automatic (without Tow Bar, Non-xDrive \u0026amp; N20 Engine Only), which needs the \u003ca href=\"\/products\/milltek-decat-downpipe-bmw-3-series-f30-328i-m-sport-automatic-no-tow-bar-non-xdrive-n20-12-15\"\u003eMilltek Downpipe \u0026amp; De-cat BMW 3 Series F30 328i M Sport Automatic (without Tow Bar, Non-xDrive \u0026amp; N20 Engine Only) 12-15\u003c\/a\u003e; the BMW 3 Series E30 M3, which needs the \u003ca href=\"\/products\/milltek-full-exhaust-with-cat-bypass-bmw-3-series-e30-m3-87-92\"\u003eMilltek Full Exhaust \u0026amp; Cat Bypass BMW 3 Series E30 M3 87-92\u003c\/a\u003e.\u003c\/p\u003e\n\u003ch3\u003eInstallation\u003c\/h3\u003e\n\u003cp\u003eThe fitting time varies by version; see the specification table for the option you choose. Some versions: Secondary Cat Bypass - Non Resonated - Fits to OE Downpipes \u0026amp; Axle Back System Only - Requires OE system to be cut. Some versions: Secondary Cat Bypass - Non Resonated - Fits to OE Downpipes \u0026amp; Milltek Sport Axle Back System Only. Some versions: Secondary Cat Bypass - Resonated - Fits to OE Downpipes \u0026amp; Axle Back System Only - Requires OE system to be cut. Some versions: Secondary Cat Bypass - Resonated - Fits to OE Downpipes \u0026amp; Milltek Sport Axle Back System Only. This work involves removing parts close to the turbo and engine, so we recommend fitting by a specialist with a ramp and suitable software support.\u003c\/p\u003e\n\u003ch3\u003eUpgrade Further\u003c\/h3\u003e\n\u003cp\u003eAlso available from Milltek for this car: \u003ca href=\"\/products\/milltek-filter-back-exhaust-bmw-3-series-g80-g81-m3-comp-s58-3-0-turbo-opf-gpf-touring-xdrive-20\"\u003eMilltek Filter-back Exhaust BMW 3 Series G80 G81 M3 Comp S58 3.0 Turbo OPF\/GPF Touring XDrive 20+\u003c\/a\u003e.\u003c\/p\u003e\n\u003ch3\u003eWhat's the difference between the resonated and non-resonated versions?\u003c\/h3\u003e\n\u003cp\u003eThe resonated version adds extra silencing for a quieter, more refined tone. The non-resonated version leaves it out, so it is louder and more aggressive.\u003c\/p\u003e\n\u003ch3\u003eWill it fit the BMW 4 Series G82 M4 \u0026amp; M4 Competition S58 3.0 Turbo (North American\/ROW Non-OPF\/GPF Cars Only)?\u003c\/h3\u003e\n\u003cp\u003eYes. Milltek lists this part for the BMW 4 Series G82 M4 \u0026amp; M4 Competition S58 3.0 Turbo (North American\/ROW Non-OPF\/GPF Cars Only) as well as the other models in the fitment list above.\u003c\/p\u003e\n\u003ch3\u003eDoes it fit the BMW 3 Series F80 M3 \u0026amp; M3 Competition Saloon (Non OPF\/GPF Models Only)?\u003c\/h3\u003e\n\u003cp\u003eNo. For that car, choose the \u003ca href=\"\/products\/milltek-decat-downpipe-bmw-3-series-f80-m3-comp-saloon-non-opf-gpf-14-18\"\u003eMilltek Downpipe \u0026amp; De-cat BMW 3 Series F80 M3 \u0026amp; M3 Comp Saloon Non OPF\/GPF 14-18\u003c\/a\u003e.\u003c\/p\u003e\n\u003ch3\u003eIs it road legal?\u003c\/h3\u003e\n\u003cp\u003eNo. Removing the catalyst means the car will fail an MOT emissions test, so it is for off-road and competition use only.\u003c\/p\u003e\n\u003ch3\u003eDo I need a remap?\u003c\/h3\u003e\n\u003cp\u003eA suitable remap is strongly recommended, as the engine management needs to account for the change in flow and sensor readings. Speak to your tuner before fitting.\u003c\/p\u003e\n\u003ch3\u003eCan I use it with my standard exhaust?\u003c\/h3\u003e\n\u003cp\u003eYes. Milltek lists it for use with the factory (OE) exhaust system.\u003c\/p\u003e\n\u003ch3\u003eWill removing the cat cause a warning light?\u003c\/h3\u003e\n\u003cp\u003eWithout suitable software it is likely to, as the ECU expects the readings a working catalyst gives. This is why Milltek pairs it with a remap.\u003c\/p\u003e\n\u003ch3\u003eHow long does it take to fit?\u003c\/h3\u003e\n\u003cp\u003eIt depends on the version. Milltek's fitting time for each option is shown in its specification table.\u003c\/p\u003e\n\u003ch3\u003eWhat is it made from?\u003c\/h3\u003e\n\u003cp\u003eT304L aircraft-grade stainless steel, which is anti-magnetic and resists discolouration better than lower grades.\u003c\/p\u003e","brand":"Milltek","offers":[{"title":"Non-Resonated \/ Twin 76mm \/ OE Axle-Back","offer_id":56392780743041,"sku":"MIL-SSXBM1270","price":795.59,"currency_code":"GBP","in_stock":true},{"title":"Non-Resonated \/ Twin 76mm \/ Milltek Axle-Back","offer_id":56392780775809,"sku":"MIL-SSXBM1268","price":801.62,"currency_code":"GBP","in_stock":true},{"title":"Resonated \/ Twin 76mm \/ OE Axle-Back","offer_id":56392780808577,"sku":"MIL-SSXBM1269","price":1010.63,"currency_code":"GBP","in_stock":true},{"title":"Resonated \/ Twin 76mm \/ Milltek Axle-Back","offer_id":56392780841345,"sku":"MIL-SSXBM1267","price":1016.66,"currency_code":"GBP","in_stock":true},{"title":"Non-Resonated \/ 102mm Single \/ Milltek Axle-Back","offer_id":56392780874113,"sku":"MIL-SSXBM1340","price":807.47,"currency_code":"GBP","in_stock":true},{"title":"Non-Resonated \/ 102mm Single \/ OE Axle-Back","offer_id":56392780906881,"sku":"MIL-SSXBM1339","price":801.45,"currency_code":"GBP","in_stock":true},{"title":"Resonated \/ 102mm with X-Pipe \/ Milltek Axle-Back","offer_id":56392780939649,"sku":"MIL-SSXBM1341","price":852.68,"currency_code":"GBP","in_stock":true},{"title":"Resonated \/ 102mm with X-Pipe \/ OE Axle-Back","offer_id":56392780972417,"sku":"MIL-SSXBM1342","price":846.66,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0667\/3232\/7161\/files\/SSXBM1270_1_d578b353-2398-4da6-9e38-24a4f7d07350.jpg?v=1791892377","url":"https:\/\/milltekexhaustshop.com\/products\/milltek-secondary-catalyst-bypass-bmw-4-series-g82-m4-comp-s58-3-0-turbo-na-row-non-opf-gpf-21","provider":"Milltek Exhaust Shop","version":"1.0","type":"link"}