Full Technical Breakdown

Designed for the factory turbocharger setup, this downpipe improves exhaust efficiency, reduces restriction, and supports higher power output while maintaining excellent fitment and durability.

Manufactured from high-quality 304 stainless steel using a combination of precision casting and welding, the JDY B58 Downpipe is built for strength, heat resistance, and long-term reliability in high-performance applications.

Key Features

4.5-Inch High-Flow Design

The JDY B58 Downpipe features a large 4.5-inch turbo outlet design, providing improved exhaust flow compared with many standard aftermarket options. The increased diameter helps reduce back pressure and allows the B58 engine to breathe more efficiently, especially on tuned or higher-power setups.

Cast Construction for Strength and Fitment

The main section is produced using a cast design, allowing smoother internal transitions and better packaging around the turbocharger area. Compared with fully welded designs, the cast section offers improved sealing performance and helps reduce the risk of cracking or exhaust leaks under high heat and pressure.

Available in Catted and Catless Options

The catted version uses a large 200-cell catalytic converter with a 130mm diameter, providing increased flow area while keeping the catalyst positioned close to the turbocharger for improved efficiency.

The catless version is designed for maximum exhaust flow and is intended for racing or off-road use where permitted.

Smooth Internal Flow Path

The cast runner design provides a smooth and consistent exhaust path with fewer sharp transitions. This helps reduce turbulence, improve exhaust gas velocity, and support better turbo response.

Wide Fitment Compatibility

Designed to fit B58 Gen2-powered BMW M240/340/440 and Toyota GR Supra applications. The downpipe is available to support both left-hand-drive and right-hand-drive vehicle layouts, depending on the selected version.

OEM Midpipe Compatibility

The outlet features an 89mm internal to 80mm external transition, designed to connect with the factory-size midpipe section for easier installation and improved compatibility.

TIG welded Back Purged

Welded sections are inspected to ensure strength, durability, and proper sealing, helping deliver consistent product quality for performance use.

Product Specifications

Product Name: JDY B58 Downpipe
Fitment: BMW M240/340/440 / Toyota GR Supra with B58 Gen2 engine
Material: 304 Stainless Steel
Construction: Cast +TIG Welded
Turbo Application: Factory B58 Turbocharger
Main Diameter: 4.5-inch
Catted Option: 200-cell catalytic converter, 130mm diameter
Outlet Size: 89mm internal to 80mm external transition