Mad 3.5″ Fat Boy Downpipes for BMW M2 G82, M3 G80, and M4 G82

Description

The MAD BMW S58 3.5″ Fat Boy Downpipes are a high-flow exhaust upgrade engineered specifically for the S58-powered M2, M3, and M4 (G87, G80, G82, G83). Designed to replace the restrictive factory downpipes with free-flowing 3.5″ tubing and large-diameter bends, these downpipes reduce backpressure and optimize turbo efficiency for quicker spool, improved throttle response, and better overall performance. Built from premium 304 stainless steel with precision TIG welding, the Fat Boy Downpipes deliver robust durability and enhanced exhaust tone without compromising drivability. Ideal for enthusiasts pursuing both street and track gains, this upgrade lays the foundation for significant performance improvements, especially when paired with a high-flow cat-back system or tuning.

Fitment Notes

• Designed to fit BMW M2 (G87) chassis with S58 engine

• Fits BMW M3 (G80) and BMW M4 (G82, G83) with S58 engine

• 3.5″ diameter design fits existing factory hangers and turbo outlets

• Professional installation recommended for best alignment and safety

Included

• One (1) MAD S58 Fat Boy Downpipe set (left and right)

• Precision-formed stainless steel tubing and collector sections

• Required mounting hardware for direct fitment

• Installation instructions

Product Specs

• Downpipe Tubing Size: 3.5″ diameter (larger than factory for freer flow)

• Material: 304 high-grade stainless steel with corrosion-resistant brushed finish

• Welding: TIG welded joints for strength and leak-free performance

• Compatibility: Designed specifically for S58 engine chassis (G87/G80/G82/G83)

• Exhaust Path: Improved free-flowing design for turbo efficiency and power delivery

Product Features

• Large 3.5″ diameter tubing reduces backpressure and enhances turbocharger efficiency

• Precision TIG welding ensures strong, durable joints under high heat and boost

• Performance-oriented flow design improves throttle response and potential power output

• Premium 304 stainless steel construction for corrosion resistance and long life

• Enhanced exhaust tone adds a richer, more aggressive sound character

• Direct-fit design bolts onto factory components for a clean installation

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