High-Flow Heat Shielded Catless Downpipe (BMW B58)

RPM Tuning 304 Stainless Steel High-Flow Heat Shielded Catless Downpipe – BMW B58 Engine

Unleash Maximum Performance and Precision Engineering.

(Replaces OE Part No. 18328631625)

Transform your BMW 3.0L into a true powerhouse with the RPM Tuning 304 Stainless Steel High-Flow Heat Shielded Catless Downpipe. Specifically engineered for the legendary B58 engine, this downpipe is your key to unlocking serious gains in power, throttle response, and sound—all while maintaining the highest levels of quality and craftsmanship.

Sizing:

4.5 Inch Turbo Side
3.0 Inch Exhaust Side

✅ Premium Build Quality & Materials

✅ Top Quality 304 Stainless Steel

• Premium-grade stainless steel for superior durability and corrosion resistance

• Built to withstand extreme exhaust temperatures without warping or cracking

✅ Precision TIG Welding

• Each downpipe is TIG-welded by expert fabricators for flawless seams and perfect fitment

• Guarantees robust strength and smooth internal surfaces for optimal exhaust flow

✅ Perfect OEM Fitment

• Direct bolt-on replacement for the stock downpipe

• Designed for seamless integration with factory or aftermarket exhaust systems

✅ High-Flow Catless Performance

• Removes the restrictive OEM catalytic converter, dramatically improving exhaust flow

• Lowers backpressure for faster turbo spool and increased power output

• Ideal for B58 engines running Stage 1, Stage 2, or even higher performance levels

• Delivers substantial gains in horsepower and torque, transforming how your M340i responds to throttle input

✅ Integrated Heat Shield – Critical Thermal Protection

The B58 generates significant heat under boost. That’s why the RPM Tuning downpipe features a fully integrated thermal heat shield for critical protection and performance:

• Retains exhaust heat within the pipe, minimizing radiant heat soak in the engine bay

• Shields surrounding components—including wiring, intake plumbing, and sensors—from damaging heat exposure

• Helps maintain lower Exhaust Gas Temperatures (EGTs), protecting your turbocharger and engine internals under hard driving

• Ensures consistent power delivery and engine reliability during aggressive driving or track use

Without effective heat shielding, excessive heat can steal performance and lead to long-term damage. Our heat shield ensures your M340i stays cool—even when you push it to the limit.

✅ Signature Exhaust Note

• Adds an aggressive, sporty tone that brings out the true voice of the B58 engine

• Delivers a crisp, deep exhaust note without overwhelming cabin drone

✅ Lifetime Warranty for Confidence

At RPM Tuning, we back our craftsmanship with confidence. All our downpipes are covered by a Lifetime Warranty, underscoring our commitment to quality, performance, and durability.

✅ Compatibility For Following Models:

1 Series F20 LCI (09/2015 — 06/2019)  
1 Series F21 LCI (09/2015 — 06/2019)  
2 Series F22 (09/2015 — 06/2017)  
2 Series F22 LCI (09/2016 — 06/2021)  
2 Series F23 (09/2015 — 06/2017)  
2 Series F23 LCI (10/2016 — 07/2021)  
3 Series F30 LCI (10/2014 — 10/2018)  
3 Series F34 GT LCI (09/2015 — 09/2020)  
4 Series F32 LCI (05/2016 — 06/2020)  
4 Series F33 LCI (05/2016 — 07/2020)  
4 Series F36 Gran Coupé (03/2015 — 02/2017)  
4 Series F36 Gran Coupé LCI (05/2016 — 05/2021)  
5 Series G30 (11/2015 — 06/2019)  
5 Series G38 (02/2016 — 08/2019)  
5 Series G31 Touring (03/2016 — 06/2019)  
6 Series G32 GT (09/2016 — 06/2019)  
7 Series G12 (10/2014 — 02/2019)  
X3 G01 (10/2016 — 07/2019)  
X4 G02 (03/2017 — 07/2019)