Competition Series 4.5" Catless Downpipe B58 Engine (G Chassis) - G20

Earn Reward Points: 490

Dollar Value of Points: $4.90

SKU: BM-EXH018

Our Competition Series 4.5" Downpipes for your 2020+ M340i six cylinder B58 turbo engine!

Key Features:

• Fitment for the new BMW B58 Engine
• Higher Max Horsepower Power Curve
• Higher Intial Torque Curve.  Torque curve hits faster, higher, and longer
• Better throttle response and faster turbo spool up times
• Mandrel Bent 4.5" 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
• Brush Finish (standard) or optional Polish 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)
• 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 4.5" Catless Downpipe, more power is unleashed!You will feel the difference instantly. While the 32whp and 16wtq gains are awesome, one of the best aspects of the downpipe is that the gains are not just peak gains. Examine the dyno graphs and you will notice the powerband shifting to the left. What this means is that turbo lag is reduced with power coming on faster. Gains are throughout the powerband as well. Your car will feel like a totally different beast. As if it had woken from it's sleep!

SO WHY 4.5" PIPING? The new turbochargers on the B58 engines utilize a much larger 4.5" outlet compared to the 4" outlet on the older N55 engines. If we ran a 4" downpipe flange inlet so that we can use 4" tubing, a "step" would be formed between the turbocharger outlet and downpipe inlet. Exhaust gas for the turbocharger would hit this "step" and a lot of turbulence would form at this point and cause backpressure. Backpressure this close to the turbocharger would greatly affect performance. Thus, to ensure that we get unobstructed flow from the turbocharger outlet to the downpipe inlet, we had to CNC machine a new 4.5" flange to match. This allows a seamless transition and eliminate any possible turbulence which would cause backpressure. Though this presented another challenge for us as 4.5" tubing is not readily available and hard to source. Our motto "Performance, No Compromise" prevailed at the end and through hard diligence and many phone calls, we finally found a source for the material.  Even though the material was considerably more expensive than standard 4" stainless steel, we wanted to give our customers the best by producing the best product possible.

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 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 4.5" and the factory exhaust system is 3", the factory downpipes reduces size using short transitions from 4.5" before the catalytic convert and 3" afterwards. Due to space needed for the cataylic converter, the factory downpipes reduce in size using very short transitions. Since our catless downpipes delete the cataylic 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. Also, since we utilize a larger 4.5" pipe right after the turbocharger, turbo backpressure is significantly reduced. This results in less exhaust turbulence and backpressure which again improves throttle response and increase turbocharger spool times (less turbocharger lag). 

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