4-inch High-Flow Stainless Steel Downpipe for BMW N55 Engine

Maximize flow, power, and sound for your N55.

Unlock the full performance of your BMW N55 engine with this massive 4-inch (101mm) stainless steel downpipe by UNILITE. Designed for maximum exhaust gas evacuation, this downpipe significantly reduces backpressure compared to the restrictive stock unit, allowing your turbo to spool faster and delivering substantial gains in horsepower and torque.

Constructed from premium SS304 Stainless Steel with a durable 1.5mm wall thickness, this pipe is built to handle the extreme heat of turbocharged driving. The oversized 4-inch diameter tapers smoothly to fit your exhaust system, ensuring optimal flow dynamics. Featuring thick, warp-resistant flanges and precision TIG welding, this unit ensures a long-lasting, leak-free seal.

Key Features & Benefits

• Massive 4-Inch Diameter: The large bore design maximizes exhaust flow, significantly reducing thermal stress on the turbo and improving throttle response.

• Premium Construction: Main piping is crafted from SS304 Stainless Steel, offering superior rust protection and thermal stability.

• Heavy-Duty Flanges: Engineered with 10mm–12mm thick flanges (available in Stainless or Mild Steel options) to prevent warping and ensure a flat sealing surface.

• Precision TIG Welding: High-quality TIG welds provide uniform strength and a clean aesthetic, reducing the risk of cracking.

• Customizable Finish: Available in Mirror Polished, Brushed, or Sandblasted finishes to suit your preference.

Technical Specifications

Packaging & Delivery

• Selling Unit: Single Item

• Package Dimensions: 45 x 20 x 17 cm

• Gross Weight: 2.500 kg

• Packaging: Secure Standard Carton

Fitment Note: The N55 engine was used in various BMW models (E9x 335i, E8x 135i, F2x M235i, F3x 335i/435i, F87 M2). Please confirm if your specific vehicle requires a 3.5" or 4" connection, and whether it uses a Pneumatic (PWG) or Electronic (EWG) wastegate, as fitment may differ.