One of the first modifications generally made to a turbocharged car is an upgraded downpipe. For over a decade, COBB downpipes have been the status quo when it comes time to upgrade your Subaru, Mazda, Mitsubishi, Ford, and more. Featuring quality stainless tubing and CAD-designed cast bellmouths, our downpipes are the best fitting and most proven on the market. This year, we set out to make the best downpipes available even better. Our most popular downpipes are receiving updates to improve overall fitment, ease installation, and maximize durability.
GESi High Flow Catalytic Converters
G-Sport by GESi prides itself on building the highest quality emissions solutions. To address the needs of performance enthusiasts all of their G-Sport models incorporate the company’s C3 Process in constructing each catalytic converter with high-grade stainless steel inside and out. Their metallic core is furnace-brazed and held in place with a Double-lock technology to ensure it will not telescope like lower-quality solutions on the market. We have been working in partnership with GESi to create a proprietary catalyst for a number of our applications and will have more in-depth information regarding that process in an upcoming blog post and video.
Typical catalytic converters include ceramic substrates that have a higher rate of cracking, degradation or cause too much back pressure in a car’s exhaust. G-Sport Emissions Systems High Performance GEN1 Catalytic Converters are designed with a 304 stainless steel substrate for added durability. The substrate is then lined with nickel strips, and furnace-brazed to provide a solid bond throughout the core and to its mantle. This process, and our ‘Double-Lock’ transition cone application, ensure the core will not telescope or fail in high performance environments.
For best emissions control capabilities without performance degradation, G-Sport designed their high flow catalytic converters with 300 or 400 cells per square inch (CPSI). Their advanced substrate design, combined with a proprietary wash coat nano-technology, ensures the highest level of emissions reduction with comparable flow rates of similar 200 CPSI converters on the market.
3″ Cast Flange
Introducing an all new cast stainless 2-bolt 3″ flange aids in both more precise assembly and also reduces stress during installation of the part. Many downpipes utilize a laser cut plate flange at the termination point to the cat-back exhaust. These plates are susceptible to minor warping while they are being welded to the tubing. A cast flange is much more rigid and reduces the possibility of flex while exposed to extreme heat during assembly. This rigidity also comes into play during installation of the downpipe. In the past, we have received reports of warped flanges during installation due to over tightening of the hardware. Over time, this deflection can lead to exhaust leaks. The new cast version, combined with hardware improvements outline below, will not bend during installation and will allow for a much more reliable seal.
Since their inception, our Subaru downpipes have necked down at the junction to the cat-back to allow for the use of the Subaru OE donut gasket. There has long been a perception that this neck-down would create a significant reduction in airflow and limit power output. Luckily, that is not true for an overwhelming majority of customers who retain the factory turbocharger or use a small frame bolt-on turbocharger. In an effort to appease those who would like to take modifications beyond the basic bolt-on level, we have now utilized full 3″ tubing all of the way to the new 3″ cast flange described above. This allows for direct compatibility of exhaust systems that use a 3″ flat flange. For those who would rather continue to use the factory or factory-replacement cat-back exhaust systems, such as the COBB 3″ Stainless Steel Cat-Back, an adapter will now be included that allows for utilization of the OE donut gasket. All new robust multi-layered steel gaskets are now included and provide a superior seal between the adapter and downpipe or to your 3″ flanged cat-back.
We all know the struggle with factory spring bolts. It’s a ballet of the fingers to get everything aligned, gasket in place, and apply just enough pressure to the spring to get the bolt threaded. An all new set of machined shoulder nuts, dubbed “B’s Nuts” internally, allow for trouble-free installation when utilizing factory spring bolts. These nuts allow you to start threading the bolt prior to adding tension by compressing the spring.
The following downpipes have received updates and are available for purchase at cobbtuning.com.
The COBB GESi Catted 3″ Downpipe is one of the key upgrades for the MAZDASPEED3 to unluck a huge amount of torque hidden away within the MZR 2.3 DISI Turbo engine from the factory. Considerable effort was spent designing a flow path with the fewest number of directional changes and minimal degrees of bend in order to eliminate restrictions that have been found in the stock system. The COBB downpipe delivers significantly improved exhaust flow, resulting in faster turbo response time and power gains across the entire rev range. This new version includes a GESi high flow catalytic converter that allows our Calibration Team to leave efficiency codes enabled in COBB created Off The Shelf Maps.
The COBB Tuning GESi Catted 3″ Downpipe begins with a CAD designed cast bellmouth that smoothly blends air exiting the turbocharger’s turbine housing. Minimizing turbulence when exhaust gasses from the wastegate join into those flowing through the turbine helps to prevent excessive back-pressure. The cast housing is capped off with a COBB logo and auxiliary O2 bung for those wanting to install a wideband sensor early in the exhaust path.
A welded bracket utilizes the factory hard mount near the transmission reducing stress on the turbocharger mounting bolts and studs.
Corrosion resistant and mandrel bent 3″ 304 Stainless Steel tubing carries exhaust gasses down stream into a COBB-exclusive GESi 300 cell high flow catalytic converter. A second O2 bung is located directly after the catalytic converter and is to be used by the OEM Rear O2 sensor.
A CAD designed, cast 304 stainless steel, flange finishes off the tail section of the downpipe. The reinforced cast flange is less susceptible to warp during assembly and for those of you installing with the strength of The Hulk. A stainless adapter flange and included MLS gasket allows direct fit with the factory exhaust or COBB Cat-Back Exhaust utilizing the OEM donut gasket. Included COBB proprietary shoulder nuts allow for installation of the factory spring bolts without fuss.
Free up your Focus ST’s exhaust flow with the COBB 3″ GESi Catted Downpipe!
This direct replacement for the factory downpipe features a 300 cell high flow catalytic converter and 304 stainless steel tubing. The CNC machined v-band flange and 4″ flex section ensure perfect OEM-like fitment at the turbocharger. We’ve added adjustability to the lower downpipe mount by slotting the attachment points. This allows installers to custom-fit each downpipe to a specific car where tolerances may be slightly off. Doing this reduces strain on the rubber isolaters, improving long-term reliability. An all new cast stainless 2-bolt 3″ flange aids in both more precise assembly and also reduces stress during installation of the part. Many downpipes utilize a laser cut plate flange at the termination point to the cat-back exhaust. These plates are susceptible to minor warping while they are being welded to the tubing. A cast flange is much more rigid and reduces the possibility of flex while exposed to extreme heat during assembly. This rigidity also comes into play during installation of the downpipe. In the past, we have received reports of warped flanges during installation due to over tightening of the hardware. Over time, this deflection can lead to exhaust leaks. The new cast version will not bend during installation and will allow for a much more reliable seal. To cap it off, a multi-layer steel gasket is used between the downpipe and cat-back exhaust to make for a leak-free junction.
All of these features combine to provide a free flowing exhaust outlet for high energy exhaust gases to reduce turbo back pressure and increase turbo efficiency.
This downpipe is the perfect step towards Stage 3 power! Stage 3 off-the-shelf maps are available for the Focus ST Accessport for a perfectly tuned out-of-the-box experience.
Updated versions of COBB Downpipes for the following vehicles are currently being worked on and will be available in the near future.
2016-2018 Focus RS
2014-2019 Ford Fiesta ST
2002-2007 Subaru WRX/STi
2019-2020 Subaru WRX STI
2005-2009 Subaru Legacy GT AT
2015-2020 Subaru WRX 6MT/CVT
2008-2015 Mitsubishi EvoX/Ralliart
2015-2020 VW GTI/Audi A3 FWD
2015-2020 VW Golf R/Audi S3, A3 AWD
2010-2014 VW GTI