Exhaust› Exhaust Pipes, Systems and Components

Ipos

4-Inch Catless Downpipe

$700.00

SKU: B46 True 4-Inch Catless Downpipe

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Special Order
Ships in 4–6 weeks
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$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The IPOS B46 True 4-Inch Catless Downpipe is an exhaust component designed for the B46 engine. This downpipe features a 4-inch diameter for maximum exhaust flow, extending all the way until after the flex pipe. It is designed to bolt up to your stock exhaust and can be modified for a true 4-inch custom exhaust by cutting and welding after the flex pipe.
Show original supplier description
The IPOS B46 True 4-Inch Catless Downpipe is engineered to maximize exhaust flow for the B46 engine. Featuring a full 4-inch diameter until after the flex pipe, this downpipe offers enhanced performance potential. It is designed to bolt directly to your stock exhaust system, with the option to be easily modified for a true 4-inch custom turbo-back exhaust by cutting and welding after the flex pipe. Installation is simplified by the inclusion of a free 3-inch v-band clamp, designed to overcome the common issues associated with seized OEM clamps and poor-design exhaust leaks. The downpipe itself is constructed to be the largest currently available on the market. Optional additions include Heatshield Products Lava Exhaust Wrap to help keep the engine bay cooler and a Downpipe to Turbo Gasket, which is required for any downpipe swap. This downpipe is specifically designed to fit the stock Gen 1 B46 and Gen 2 B46TU exhaust systems, covering models such as the 230i, 330i, 430i, 220i, 320i, and 420i. It is explicitly stated that this downpipe **will not fit on a B48** engine. The manufacturer notes that most B4x engines in North America are B46 variants, and advises customers to contact them if unsure about compatibility.
Vehicle Symptoms
  • Check engine light on for P0420 catalytic converter
  • Car feels sluggish under acceleration
  • Exhaust smell in cabin during idle
  • Turbo spools slower than before
  • Want louder, more aggressive exhaust note
Diagnostic Codes
  • P0420:Cat Sys Efficiency Below Threshold (B1)
Relevant Conversations
  • How to fix P0420 on B46 engine
  • Catless downpipe vs catted downpipe B46
  • IPOS 4-inch downpipe review
  • B46 downpipe install time and difficulty
  • Will catless downpipe cause check engine light
  • Best downpipe for B46 turbo upgrade
  • Downpipe plus tune for B46
  • 4 inch downpipe vs 3.5 inch downpipe B46
  • O2 spacer for P0420 after downpipe
  • B46 downpipe with flex pipe location

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

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Specifications

BrandIpos
Part NumberB46 True 4-Inch Catless Downpipe
CategoryExhaust
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