4 Series BMW Diffuser Carbon Fiber 2014-2020

Unleash the untamed spirit of your BMW 4 Series with the 2014-2020 BMW 4 Series Diffuser – a daring and audacious upgrade that redefines the rear end of your vehicle, combining aggressive aesthetics with unparalleled performance flair.

Constructed from top-tier materials, the diffuser is not just a visual upgrade – it's a durable accessory built to withstand the demands of the open road. Revel in a lasting enhancement that not only resists wear and tear but also exudes a rugged elegance, ensuring your BMW remains a head-turner for years to come.

FREE shipping within the Continental U.S. for Headlights, Taillights, DRLS, and Carbahn Controllers. Shipping rates apply towards Exterior and Performance products.

Worldwide shipping available, rates automatically processed through check-out.

Please note, for retrofits, you are paying for a headlight modification service which requires you to ship us your headlights (does not apply to our DRL products). The service itself includes the installation of rings and associated parts but does NOT include new headlights.

If you require new headlights at an additional cost to start with, please select Purchase new OEM headlights from the headlight option selection.

If you select Shipping own headlights to Bayoptiks for modification, you are required to ship your headlights to us. Once we are done completing your customizations, shipping your order will be free of charge if you live in the Continental US.

Headlights: At this time, typical turnaround times for for ship-in and pre-built headlights can range between 6-8 weeks depending on the complexity of the build and availability of components.

New OEM headlights and cores require an additional 4-8 weeks lead time. New OEM headlights are a special order based on the vehicle VIN due to different versions e.g LHD, RHD, North America, European, etc.

DRLs & Taillights: Please allow 3-5 business days for order processing followed by shipping.

Please note, we do not have control over the time frames of our vendors, manufacturers, and delivery services as they may delay processes in regards to components and shipment. 

All sales are final across all of our headlight, taillight, and carbon fiber products and we do not accept returns.

We can only exchange taillights/carbon fiber for the same model taillights/carbon product if there is a defect which needs to be verified and evaluated via photo and video proof.

Due to the customized nature of headlight orders, custom headlight build cancellations are subject to a 25% non refundable fee unless it is a special case (e.g. transfer of ownership of the vehicle) which require documentation and we determine if the fee is applicable or not on a case by case basis. The 25% cancellation fee is required due to special order/unique/non-refundable parts as well as labor and services rendered. 

We recommend professional removal and installation of the headlights and we are not liable for any damage incurred from self installation. In some instances, coding may be required for the headlights for all features to function 100% correctly. Coding and associated fees are the responsibility of the buyer.

Each headlight retrofit we offer features a 1 year warranty which covers against any defects related to service performed by BayOptiks. This warranty only covers the original purchaser of the retrofit and cannot transfer to future owners. After 30 days of receiving the retrofitted BayOptiks headlights, the customer is required to pay for shipping costs related to warranty repair work; we take care of the warranty related service as well as the return shipping costs for U.S. customers. International customers are required to pay for shipping costs to us and return shipping. Any labor costs associated with headlight removal/reinstallation are the  sole responsibility of the original purchaser. BayOptiks does not reimburse for any labor costs associated with headlight removal/reinstallation.

For taillight products, the 1 year warranty only covers the original purchaser and cannot transfer to future owners. After 30 days of receiving BayOptiks taillights, the customer is required to pay for shipping costs related to warranty exchanges, we take care of the warranty replacement in compliance with the manufacturer requirements as well as the return shipping costs.