The ARM F3X N55 4" Downpipe is the best hardware upgrade for getting the most power from your N55-powered F-Series BMW. The stock downpipe's catalyst severely restricts exhaust flow — upgrading unlocks power, improves turbo spool, enables Stage 2+ tuning and opens up the exhaust note, all at once. Highlights Gains of up to 23 whp / 29 wtq. Faster turbo spool and improved exhaust sound. Enables Stage 2+ tuning. SS304 stainless steel. Construction Mandrel-bent SS304 starting with a 4" precision CNC-machined turbo V-band connection that gradually reduces to a flared joint to optimise flow while matching the stock midpipe V-band perfectly. Two O2 sensor bungs, located higher up, avoid stretching the sensor wires. A tune or CEL Delete is required to avoid a check-engine light. Stage 2 N55s can see around 400 whp / 400 wtq (most tunes also need an FMIC upgrade — see the ARM F3X FMIC). Fitment (N55 3.0L, 4" EWG turbocharger only) BMW F20/F21 M135i, F22/F23 M235i, F30/F31/F34 335i, F32/F33/F36 435i (incl. Gran Coupe), F87 M2 (incl. xDrive). What's included: ARM N55 downpipe. Backed by ARM Motorsports' lifetime warranty against defects in craftsmanship and fitment. Emissions disclaimer: This product is intended for off-road, race, or closed-course competition use only and is not legal for use on pollution-controlled vehicles operated on public roads in most states and provinces. You are responsible for compliance with all applicable emissions laws. Please check your local laws before purchase and installation. Ships from our Vancouver shop — KORE SPEED is proudly Canadian-owned, with no surprise cross-border duties for Canadian buyers. Questions on fitment? Email [email protected].
