Product Details
About this part
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:
- 2025+ BMW M340
- 2025+ BMW M440
Fitment
Not sure it fits? Contact us with your car's year, model and VIN and we'll help you confirm before you order.
If a part doesn't fit as expected, contact us and we'll work with you to resolve it.
Majority of products have a fitment section in the product description or within the title.
Returns
- Unused, uninstalled parts can be returned or exchanged within 30 days of the order date.
- To start a return: Contact us first, don't use Return to Sender.
- Returns can have up to a 20% restocking fee.
- Built-to-order and special-order items can't be returned or cancelled once production begins.
Shipping
- Orders are processed 7 days a week to ensure your product ships as quickly as possible.
- Inspect parts within 10 days of delivery, and reach out regarding any damage or missing pieces.
See our Tariff Policy
Warranty
- All parts retain the manufacturer's warranty.
- Warranty claims are subject to the manufacturer's approval.