Downpipe Exhaust For N54 V2 2007-2010 BMW 335i / 2008-2012 BMW 135i | SPELAB

Who This Is For

2007-2013 BMW 335i (E90/E92/E93) and 2008-2012 BMW 135i (E82/E88) / 1M Coupe owners with the N54 twin-turbo engine who want a 3" catless downpipe for faster turbo spool, stronger mid-range torque, and a more aggressive exhaust note.

Key Features

• Adds 20-25 whp and 25-30 wtq (measured on engineering prototype, with Stage 2 tune)
• CAD/CAM-designed cast bell mouth for seamless flange-to-pipe transition
• Mandrel-bent, TIG-welded 3" 304 stainless steel
• Smooth radius bends reduce turbulence and increase flow
• Fits both LHD and RHD models with no modification

Product Specifications

• Engine: BMW N54 3.0L Twin-Turbo
• Pipe Diameter: 3 inch
• Material: 304 Stainless Steel
• Configuration: Catless (removes factory catalytic converter)
• Flange Type: Bolt-on (2-Bolt)
• Weight: 4.62 kg (4620 g)

What's Included

• Downpipe (pair — twin-turbo)
• Gaskets
• Mounting hardware

Check Before Choosing

• CEL behavior: A catless N54 downpipe triggers a P0420 catalyst-efficiency CEL. Suppress with MHD or JB4 Stage 2 tune; O2 spacers are unreliable.
• Tune required: Yes — a Stage 2 tune is required to suppress the CEL and safely reach the full power gain.
• N55 exclusion: Does NOT fit the N55 (2011+ 335i single turbo). N54 and N55 use different downpipe flanges.
• LHD / RHD: Fits both LHD and RHD models with no modification.

Vehicle Fitment

Compatible vehicles: BMW 335i, BMW 335is, BMW 135i, and BMW 1M Coupe (2007–2013).

Installation Guide

Pre-Installation Checklist

• Confirm your engine code and model year match the fitment list above
• New gaskets and mounting hardware ready
• 22mm slotted O2 sensor socket + PB Blaster on hand
• a Stage 2 tune (MHD / JB4) to clear CEL

Installation Steps

1. Lift the vehicle and secure it on jack stands
2. Soak the O2 sensors and flange bolts with PB Blaster for 30+ minutes
3. Unplug and remove the O2 sensors with the slotted socket
4. Remove the factory downpipe and discard the old gasket
5. Bolt on the new downpipe with a fresh gasket
6. Reinstall and reconnect the O2 sensors
7. Flash your tune to suppress the check engine light

Installation Notes

• Never reuse the old gasket — it will cause an exhaust leak
• Use a slotted O2 socket, not a wrench — the sensor threads strip easily
• A catless downpipe triggers a CEL until the ECU is tuned
• Expect a stronger raw exhaust smell (normal for catless)

FAQ

Is this catted or catless?

Catless — the product helps reduce turbine-side restriction and remove factory cats.

How much power will I gain?

+20-25 whp and +25-30 wtq with Stage 2 tune (measured on engineering prototype).

Does it fit the N55?

No — the N55 (2011+ 335i single turbo) uses a different downpipe flange. N54 only.

Is it street-legal?

No — off-road / race use only under the Clean Air Act.