The ARM E-Series N55 Downpipe is engineered to increase power and performance for BMW vehicles equipped with the N55 engine. By optimizing exhaust flow and reducing back pressure, this upgrade allows your turbocharged engine to perform more efficiently.

Upgrading the downpipe on your N55 improves turbo response, increases horsepower and torque, and enables Stage 2+ tuning. It also enhances the overall exhaust sound of your 135i or 335i, making it deeper and more aggressive.

The ARM N55 Downpipe is designed for direct fitment and is compatible with both OEM and aftermarket midpipes. It features an 80mm V-Band flange, allowing it to work with both standard factory turbochargers and upgraded turbo setups.

For N55 owners seeking more power, a downpipe upgrade is one of the first and most effective hardware modifications.

Highlights

• Gain up to 21 WHP / 27 WTQ
• Faster turbo spool
• Improved exhaust sound
• Supports Stage 2+ tuning
• Constructed from SS304 stainless steel

Improved Exhaust Sound

Beyond performance gains, the ARM N55 Downpipe significantly enhances exhaust sound.

Thanks to its 4.5-inch middle section, the downpipe produces a deeper and more aggressive exhaust note, especially during cold starts and full-throttle acceleration. This design creates a more pronounced and sporty sound compared to standard 3-inch downpipe upgrades.

Construction

The ARM N55 Downpipe is built using high-quality TIG-welded SS304 stainless steel for durability and long-lasting performance.

Key construction features include:

• Precision CNC-machined 80mm V-Band flange compatible with OEM and upgraded N55 turbos

• Integrated flex section welded directly after the flange to reduce stress on the turbo during aggressive driving

• Large 4.5-inch middle section to improve exhaust flow and enhance sound

The downpipe transitions from the 4.5-inch center section into dual 2.5-inch flanges at the midpipe connection. This allows seamless integration with both OEM and aftermarket midpipes designed for the factory N55 layout.

Additionally, the downpipe includes two O2 sensor bungs, allowing you to reinstall the OEM oxygen sensors. These bungs are positioned higher on the pipe to prevent stretching the sensor wiring during installation.

In the Box

• ARM N55 Downpipe

• 2 × Midpipe gaskets

• 4 × Bolts, washers, and nuts

Fitment Guide

The ARM E-Series N55 Downpipe is designed for the following BMW vehicles equipped with the N55 3.0L engine:

ARM Motorsports Lifetime Warranty

Every ARM Motorsports product is backed by a lifetime warranty, automatically issued at the time of purchase.

This warranty protects against defects in craftsmanship or fitment and entitles you to a replacement unit if a manufacturing defect occurs.