MAD BMW B58 2025+ Gen 3 M340 M440 Fat Boy 5.0" Downpipe Catless

Upgrade your 2025+ BMW M340 M440 with the MAD BMW B58 Gen 3 "Fat Boy" 5.0" Catless Downpipe—the ultimate performance upgrade designed to unleash the full potential of your engine. Crafted from premium-quality 304 stainless steel, this larger-diameter 5.0-inch downpipe offers superior airflow, delivering enhanced horsepower, quicker turbo response, and noticeable torque gains.

The increased diameter of the "Fat Boy" downpipe sets it apart from our standard catless models by providing a deeper, richer, and significantly more aggressive exhaust tone. Precision-engineered welds and exceptional craftsmanship ensure perfect fitment, durability, and peak performance for enthusiasts demanding maximum results.

Transform your BMW M340's driving experience by choosing MAD's top-tier downpipe, designed specifically for drivers seeking ultimate airflow and a sound profile that commands attention.

Features:

• Premium 304 stainless steel for superior durability

• Expanded 5.0-inch diameter for unmatched airflow and performance

• Deeper, richer, and more aggressive exhaust tone

• Improved horsepower and torque compared to standard catless downpipes

• Precision craftsmanship and perfect bolt-on fitment

• Ideal for high-performance builds and enthusiasts seeking maximum results

Fitment:

Does not fit euro models (check downpipe flange design before ordering)

2025+ BMW M340

2025+ BMW M440

2025+ BMW X3 G45 M50

2025+ BMW X4 G46 M50

Emissions Disclaimer:
This product is not legal for sale or use on pollution-controlled vehicles operated on public roads, highways, or streets. It is intended for off-road, race, or closed-course competition use only, where such modifications are permitted.

By purchasing this product, you acknowledge and agree that:

• You are responsible for compliance with all applicable emissions laws and regulations.

• MAD and its affiliates disclaim any liability for improper or unlawful use of this product.

• Use of this part on public roads may violate the Federal Clean Air Act (42 U.S.C. § 7522) and similar state laws.

Please check your local laws before purchase and installation.

The items installed or applied to vehicles are intended strictly for off-road use only and track vehicles. These modifications may not comply with emissions, safety, or environmental regulations required for public road use under Environmental Regulatory Agency (ERA) laws. It is the sole responsibility of the vehicle owner or operator to ensure adherence to all applicable local, state, and federal regulations. Use on public roads may result in legal penalties or vehicle impoundment. Always verify compliance with local authorities before installation.

We get a large number of custom orders and requests everyday, so as a result it is not always possible for us to keep every item in stock at all times in our warehouse. If you require the item urgently please contact our sales team here to check the stock before you make your purchase.

If you're unsure whether a part will fit your vehicle, feel free to contact us here with your inquiry. Our helpful sales team will reach out to confirm if it's the right match for you.

We offer a flat-rate shipping fee across the continental United States. This excludes Alaska, Hawaii, and U.S. territories. For international orders, additional shipping costs will apply. Please contact us for a quote if you are outside the continental U.S.

Also, feel free to also contact us at ColoradoN5X@Gmail.Com for any other questions.

Not all items are covered by warranty. Items including warranty, will clearly state that there is warranty within the product description. Most of these items will be a standard 1-year warranty against manufacture defects. You, the customer, will be responsible for shipping and handling. We will fix/replace that item with a product that is in working condition if you meet the warranty criteria. Please note that you will be allowed ONLY 1 claim within the year for that product. ColoradoN5X is not responsible for any damage caused during the installation of our products.