Description
The ARM Motorsports F8X S55 Catted Downpipes are engineered to deliver substantial gains in power, torque, and throttle response while maintaining excellent fitment and a refined yet aggressive exhaust note. Designed specifically for BMW’s S55 engine, these downpipes are an essential upgrade for F8X owners looking to push performance safely and reliably.
Featuring dual 200-cell catalytic converters, the ARM F8X S55 Catted Downpipes significantly improve exhaust flow while reducing emissions smell compared to catless options. This design helps relieve exhaust back-pressure, allowing the turbochargers to operate more efficiently, especially under higher boost levels associated with Stage 2 and higher tuning.
On a Stage 2 tuned test vehicle, installation of the ARM F8X downpipes resulted in 543whp and 547wtq, representing gains of 73whp and 126wtq over stock results. Even on a factory tune, drivers will experience noticeable improvements in power delivery, throttle response, and overall driving engagement.
Performance Highlights
• Up to +30whp and +30wtq
• Improved throttle response
• Enhanced turbo spool
• Reduced exhaust back-pressure
• Deep, aggressive exhaust tone without harsh rasp
Sound Characteristics
The ARM F8X S55 Catted Downpipes are designed to deliver a bold, refined exhaust note. Unlike many aftermarket options that produce a high-pitched rasp, these downpipes emphasize a deeper, more aggressive tone that stands out under both part-throttle and wide-open throttle driving.
Construction & Design
The downpipes are constructed from high-quality 304 stainless steel with a full 3-inch diameter for maximum exhaust flow. Precision CNC-machined V-band flanges ensure a smooth transition from the turbochargers to the downpipes, improving exhaust gas velocity and reducing turbulence.
To maintain optimal flow when connecting to the factory mid-pipes, the ARM F8X S55 Catted Downpipes utilize a smooth, gradual transition from a 3-inch inlet to a 2.5-inch outlet. This design avoids the abrupt reducers found on some aftermarket systems, which can negatively impact exhaust efficiency.
Each set is engineered to route cleanly through the factory exhaust tunnel, providing OEM-like fitment with a high-quality finish.
What’s Included
• ARM F8X S55 Catted Downpipes
• CNC machined bracket for front turbo downpipe
• Four downpipe to mid-pipe bolts and nuts
• ARM Motorsports lifetime replacement warranty
Vehicle Fitment
BMW F80 M3
Engine: S55 3.0L
BMW F82 M4
Engine: S55 3.0L
BMW F83 M4
Engine: S55 3.0L
BMW F87 M2 Competition
Engine: S55 3.0L
Warranty Information
All ARM Motorsports products are backed by a lifetime warranty issued automatically at the time of purchase. This warranty covers defects in craftsmanship and fitment and entitles the original purchaser to a replacement unit if necessary.
Note: This product is for off-road use only. It is illegal to use this product on public roads in most states and provinces and is intended for racing vehicles that will never be used on public roads.
