SKU: 50430403590

Competition Series 4" Catless Downpipe for the B48 EU/Asia (4 Cylinder) Engine

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Description

Competition Series 4" Catless Downpipe for the B48 EU/Asia (4 Cylinder) EngineIntroducing our new Competition Series 4" Downpipes for your BMW B48 four cylinder turbo engine! Fits all 2016+ 120i 125i 230i 330i 430i 530i X3 30i X4 30i Z4 30i 20i. The B48 engine is found in the European and Asia spec cars. The downpipe is different than the B46 found in the U. S. spec cars. You must get the correct downpipe for your car as they are not interchangeable. Key Features: Made in the USA! Manufactured in house. Now available for the

Introducing our new Competition Series 4" Downpipes for your BMW B48 four cylinder turbo engine!  Fits all 2016+ 120i/125i/230i / 330i / 430i / 530i / X3 30i / X4 30i / Z4 30i/20i.  The B48 engine is found in the European and Asia spec cars.  The downpipe is different than the B46 found in the U.S. spec cars.  You must get the correct downpipe for your car as they are not interchangeable.  

Key Features:

  • Made in the USA!  Manufactured in house.
  • Now available for the 2016+ 120i/125i/230i / 330i / 430i / 530i / X3 30i / X4 30i / Z4 30i/20i B48 Engine!
  • Horsepower gains of 14 to 16whp average (gains will vary based on modifications of your vehicle).
  • Higher Max Horsepower Power Curve
  • Torque gains of 20 wtq average (stock boost) up to over 24 wtq (Software upgrade) (gains will vary based on modifications of your vehicle).
  • Higher Initial Torque Curve.  Torque curve hits faster and higher and longer.
  • Better throttle response and faster turbo spool up times.
  • Mandrel Bent 4" piping.  Smooth transition to the exhaust system.
  • 100% Stainless Steel Construction
  • 100% TIG welded for better quality welds
  • Precision CNC machined turbocharger V-Band flange.
  • Stainless steel flex section like factory that allows proper exhaust movement and flexibility.
  • Mirror polish or brush finish
  • Available with high temperature black thermal coating to reduce underhood temperatures.
  • Optional - Additional O2 sensor bung for wideband O2 sensors (comes with pre-installed plug)
  • Optional EGT sensor bung for EGT gauges (comes with pre-installed plug)
  • Retains the factory "ball" type v-band connector.
  • Improved design of "ball" connector for better flow characteristics over factory connector.
  • Compatible with the factory or aftermarket exhaust systems.
  • Track tested durability.
  • Includes all hardware for complete installation.
  • Limited Lifetime Warranty.

Restrictions in the exhaust system robs horsepower and torque especially on turbocharged cars.  Thus, removing as much exhaust flow restrictions will increase horsepower and torque significantly.  The factory catalytic converter found in the factory downpipe is a big culprit of this and is a major exhaust flow restriction.  The factory catalytic converter is made up of catalyst material formed into "honeycomb" weaves.  Exhaust gas must pass through these tiny "honeycomb" weaves on their way to the exhaust system thus causing a major exhaust flow restriction.  It also causes turbulence after the catalytic converter which causes the exhaust flow to slow down (which increases restriction).  By replacing the factory downpipe/catalytic converter with our Competition Series 4" Catless Downpipe, more power is unleashed!  Our dyno testing has shown around 14-16whp average peak gains and upwards of 24wtq peak gains!  While peak horsepower is nice to look at on dyno charts, what's more important is the power curve.  If you look at the dyno charts, torque hits MUCH earlier and harder.  The torque curve is BROADER throughout the RPM band.  More usable power.  You have more time spent in the RPM band with higher horsepower and torque.  This equates to faster turbo spool up (less turbocharger lag) and better throttle response.  Bottom line, faster.  You will feel the difference instantly. 

Our Competition Series Catless Downpipes is constructed out of 100% 304 grade stainless steel and utilize mandrel bent piping.  They are 100% TIG welded by our in house fabricators and built in the USA.  The factory turbocharger turbine housing utilizes a 4" V-Band flange which we have duplicated and CNC machined cut out of billet 304 stainless steel.  Stainless Steel CNC machined O2 sensor and laser cut brackets are TIG welded using stainless steel rods.  The O2 sensor is positioned at the factory location.  Since the outlet of the turbocharger is 4" and the factory exhaust system is 3", the factory downpipes reduces size using short transitions from 4" before the catalytic convert and 3" afterwards.  Due to space needed for the catalytic converter, the factory downpipes reduce in size using very short transitions.  Since our catless downpipes delete the catalytic converter, we have more space.  Thus, we use very long transitions.  These longer transitions allow the exhaust gas time to smoothly transition from the larger piping to the smaller.  This results in less exhaust turbulence and backpressure which again improves throttle response and increase turbocharger spool times (less turbocharger lag). 

The factory downpipe utilizes a flex bellow section that allows the exhaust system to move.  This eliminates undue stress on the exhaust components like the exhaust system, downpipe, turbocharger and exhaust manifold.  Many of our competitors do not feel it is important to keep this.  While you do not see any adverse affects right away, over time, the stresses caused by not having a flex section and having a rigid exhaust system will cause premature wear and tear.  Any stress failures like cracks will form quicker than usual on exhaust manifolds and exhaust components.  Also, without a flex section, the exhaust system cannot properly deflect impact.  Especially on lowered cars, whenever the exhaust system contacts the ground, the entire system gets pushed up.  Without a flex, you can imagine how much stress is put into exhaust components like the exhaust manifold when the exhaust is pushed upwards.  We fully understand that durability of our products is important.  Thus, like BMW, we incorporate a flex section into our downpipe.  Our flex sections are 100% stainless steel (cheap flex sections only have stainless steel center braids and steel caps) to ensure corrosion resistance.  

One of the main features of our B46 downpipe is the CNC machined solid stainless steel billet ball joint.  The factory downpipe uses a press formed process to produce the "ball" joint to connect to the factory exhaust.  This process can be done very inexpensively when done in large productions runs.  Unfortunately, the drawback of this press formed "ball" joint is that the interior of the pipe also mimics the outside.  When exhaust flows through a pipe, the majority of the exhaust flow tends to stay on the outer edges of the pipe.  Thus, when exhaust flows into the "ball" section, it goes into the valley created by the "ball" joint and then back up the other side.  This creates tremendous amounts of turbulence in the exhaust flow right at that section.  Turbulence in turn, slows down exhaust flow velocities as well as increase back-pressure.  It's a well known fact that with turbocharged cars, you want the least amount of back-pressure while still maintaining high exhaust flow velocities.  Why?  Because low back-pressure and high velocities allow the turbocharger to spin faster.  This equates to reducing turbocharger lag and faster spool times.  Throttle response is also improved.  We had originally thought to use the same press form process to manufacture our downpipes.  However, very quickly we noticed this flaw to the process and decided to CNC a solid stainless steel billet "ball" joint.  This allowed us to keep the factory connection while keeping the interior of the ball smooth.  This allows the exhaust to flow unrestricted through the "ball" joint.  While this CNC solid stainless steel billet was very expensive to manufacturer, our motto at ER is "Performance, no compromises".  Our in-house testing showed that we did indeed have real world improvements with this new CNC billet "ball" joint and thus worth the extra costs.  This is why the N26 downpipes do cost a little bit more than the N20 downpipes as the N20 downpipes do not have the ball joint system but use a traditional slip-fit design which is cheaper for us to manufacturer.  The pictures below show the factory "ball" joint cut in half (to show in the interior) versus our CNC solid stainless steel billet "ball" joint.

Since we are able to reproduce the factory "ball" joint v-band connector, our downpipes are designed to fit perfectly with either the factory exhaust system or your aftermarket exhaust system.  There are no compatibility issues whatsoever.  The downpipes will come by default with brushed finish.

Our downpipes are designed to fit perfectly with either the factory exhaust system or your aftermarket exhaust system. There are no compatibility issues whatsoever.  The downpipes will come by default in Brushed Finish.  We also offer a Polished Finish as an option.

OPF Compatibility (EU & Asia Spec)

Some European Spec & Asia Spec cars feature the Otto Particulate Filter (OPF) system as part of their emissions equipment.  We now offer downpipes that are compatible with the OPF system and allows you to retain full function of it.  

OPTIONS

Ceramic Thermal Coating - The purpose of ceramic coating downpipes is to keep heat from the exhaust gases inside the downpipe from radiating out. This keeps underhood temperatures lower and less heat absorption by nearby parts/surfaces.  Another added benefit is that by keeping in heat (energy) in the exhaust gases inside the downpipe, exhaust flow velocities stay up, resulting in lower backpressure. The ceramic coating also adds additional corrosion resistance. We utilize the best ceramic coating possible. Our thermal coating can resist up to 2000F of heat. It is available in black only (all the other colors cannot withstand the high levels of heat).

Additional O2 Sensor Bung - An additional O2 sensor bung can be added so that you can easily add a wideband O2 sensor and gauges for you to monitor air/fuel ratios. The additional O2 sensor bung will come pre-installed with a plug so that you do not need to run the O2 sensor right away.  This is not required for a normal standard installation.

Optional EGT (Exhaust Gas Temperature) Bung - An additional 1/8" NPT bung can be added so that you can easily add a EGT sensor and gauge. The optional EGT sensor bung will come pre-installed with a plug so that you do not need to run the EGT sensor right away.  This is not required for a normal standard installation.

CAUTION: This product is intended for OFF ROAD COMPETITION USE ONLY. Not legal for use on pollution controlled vehicles upon public road/highways. THIS PRODUCT IS FOR SALE FOR ALL 49 STATES EXCLUDING CALIFORNIA.  In addition to vehicle use verification, a Vehicle Compliance Waiver needs to be signed.

THIS ITEM IS NOT FOR SALE, INSTALLATION, OR USE ON LICENSED VEHILES IN THE STATE OF CALIFORNIA. 

The item is for sale for international customers without restriction.

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
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Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
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SKU: 50430403590

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4.4 ★★★★★
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C
Christopher West
Carnegie, US
★★★★★ 5
Great book! Practical and for developers that already use AI!
Format: Paperback
I purchased "Agentic Coding" by Claude Code due to my desire for an alternative to generic "Prompt Template" type resources related to AI-based development. This book accomplishes just that. As opposed to merely viewing Claude Code as a "magic box", the author has explained how to utilize it in conjunction with other actual development processes. The authors' emphasis on "context engineering" (i.e., structuring data/information; managing knowledge in a project; guiding an AI agent to produce consistent results vs. producing random/unknown results) represents the strongest component of the book. It should be noted that the book appears to be intended primarily for experienced developers with prior experience in software development and/or familiarity with AI-based development tools. Should you be familiar with Git, the command-line interface, and/or modern development processes, you may find this resource very helpful. Conversely, I did appreciate the fact that there were no novice-oriented descriptions provided throughout the book. The aspect of the book that I found most valuable, however, is the extremely pragmatic nature of the material contained within. The examples illustrated through developing/maintaining CLAUDE.md files; utilizing Claude Code in combination with GitHub Workflows; employing MCP Servers; and creating multi-agent or sub-agent workflows all seemed to reflect a clear focus on "real world usage" rather than theoretical constructs. In addition, each chapter builds upon previous chapters in such a manner as to provide a logical progression through which the reader can easily understand and ultimately implement the concepts learned. I also appreciated that the author included guidance on responsible utilization of the tool(s), as well as maintaining control over what changes are made by the agent. While numerous books regarding AI focus solely on what AI tools can accomplish, this book addresses both how to utilize these tools effectively in a real codebase, as well as responsibility and safety considerations. In summary, this is not a book for individuals completely inexperienced in either programming or generative AI. However, if you are currently experimenting with tools such as Claude, Cursor, GitHub Actions, or MCP, this is likely one of the more useful and practical books available on the subject. Recommended for software engineers seeking to transition from simply "prompting an AI" into establishing a repeatable/professional workflow process surrounding agentic coding.
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Reviewed in the United States on April 11, 2026
P
Paul Pollock
Dallas, US
★★★★★ 4
⭐⭐⭐⭐ (so far)
Format: Paperback
I'm maybe a third of the way through this and already rethinking how I talk to coding agents. The reframe from "prompt engineering" to "context engineering" sounds like semantics until Marco walks you through why context poisoning, context clash, the Goldilocks zone for system prompts. That chapter alone reorganized something in my head. I keep going back to the line about garbage in, garbage out being the real reason agentic systems underperform. The hands-on stuff lands well too. Building the HookHub project from scratch, wiring up Playwright MCP, watching Claude generate a CLAUDE.md file and then not automatically loading a memory file you just created — that moment where you expect magic and get silence instead? That's the kind of honest teaching I appreciate. It made the "why" behind memory hierarchies click.
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Reviewed in the United States on May 12, 2026
J
Jonathan Reeves
Lexington, US
★★★★★ 5
Essential Reading for Developers Serious About Agentic AI Workflows with Claude Code
Format: Paperback
Agentic Coding with Claude Code is easily one of the most practical and forward-thinking AI development books I’ve read. Instead of treating Claude Code like a simple chatbot, this book shows how to turn it into a true agentic development platform capable of handling real-world engineering workflows. What I appreciated most was how actionable the content is. The explanations around slash commands, hooks, persistent memory files, and MCP servers are incredibly clear and immediately useful. The author does an excellent job balancing foundational concepts with hands-on implementation, making advanced topics like multi-agent orchestration and hierarchical delegation approachable for experienced developers. The chapters on MCP and context engineering were especially valuable. Most AI books stay at the surface level, but this one dives deep into structured context sharing, workflow automation, and scalable AI-assisted development practices that actually matter in production environments. I also liked that the book focuses heavily on maintainability and control. It doesn’t just show flashy demos—it teaches how to safely integrate AI agents into existing terminal and IDE workflows while enforcing coding standards and keeping projects organized. The examples using Claude Code with Next.js projects were practical and helped connect the concepts to real software engineering scenarios. The sections on subagents, planning workflows, and reusable automation patterns opened my eyes to entirely new ways of approaching AI pair programming and development productivity. If you are a developer, AI engineer, or technical lead looking to move beyond basic prompt engineering and build reliable, scalable AI-assisted workflows, this book is absolutely worth reading. Highly recommended for anyone serious about modern agentic coding and AI-powered software development.
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Reviewed in the United States on May 9, 2026
K
Kirk D. Borne
Chelsea, US
★★★★★ 5
Agentic Coding - all the right pieces in the right places
Format: Paperback
Before obtaining a copy of this book, I had not yet become familiar with Claude Code and didn't realize how robust AI Pair Programming is now. However, I did know and have rigorously promoted the absolute importance of Context (via Context Engineering) in any AI-prompted tasks, including coding. This book brings all of that together in an incredibly useful book (dare I say... a comprehensive toolkit and handbook) for AI-prompted coding in these multiple modalities: IDE, command-line, and pair programming. It covers memory management, agents, subagents, multiple-agent systems, context-sharing, orchestration, enforcement of coding standards, code maintenance, and more - for executing AI-assisted development with confidence. I highly recommend this book. Disclosure: the publisher provided me with a free review copy of the book.
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Reviewed in the United States on May 19, 2026
C
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CATRINA S
Massapequa, US
★★★★★ 5
Perfect size for me
Color: Light Color Series, Style: Waffle Pattern, Color: Light Color Series, Style: Waffle Pattern
Washed the cloths before use with just detergent. Pretty much stayed it shape and fluffy texture. It lathers well with any soap and drys fast. Love the texture size more than the exfoliating size. Texture side is great for sensitive face cleaning. The exfoliating side did soften after repeated use. I feel it is still little to rough for the face, but great for the body. 
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Reviewed in the United States on June 18, 2025

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