One of the best ways to improve a turbo engine’s performance is to install a set of downpipes. Running a downpipe improvement on a Subaru WRX has many advantages. Downpipes, as the first piece of the exhaust system following the turbo, are crucial to force-induced engines. They are a component that can severely limit or significantly improve an engine’s output.
While the stock WRX downpipe’s cat is effective at reducing emissions, it is severely detrimental to the vehicle’s performance. Fortunately, there are a wide variety of high-quality WRX downpipes available in numerous designs to meet your specific demands. Here we’ll go through the benefits of both catless and catted downpipes for the Subaru WRX, as well as highlight a few of the greatest downpipe upgrades.
What is a Downpipe?
The section of exhaust that connects your turbocharger to your system’s catalytic converters and tailpipe is called a downpipe (DP). Turbocharged vehicles have an additional exhaust component. The Subaru WRX engine is one example of a turbocharged vehicle that also features a catalytic converter in the vehicle’s downpipe. The downpipe of a WRX from the Commonwealth of Virginia is home to two cats. There is a significant loss of power due to the cat’s restriction of exhaust flow right after the turbo. Really, that’s all there is to a downpipe. It begins at the turbo and terminates at the cat-back, complete with factory-installed cat.
Since it’s so close to the turbo, it’s the most crucial component of a turbo engine’s exhaust system. The downpipe provides the greatest gains in performance of any part of the exhaust system after the turbocharger.
Subaru WRX Downpipe Performance
The emissions of the factory WRX vehicle are lowered thanks to the catalytic converter (cat) installed in the factory downpipe. That is precisely what it accomplishes. The cats are not only quite limiting, but they also reduce power and performance. Turbos rely heavily on the pressure decrease from before to after the turbo to spool. Therefore, quicker spool and increased power can be achieved by decreasing back-pressure after the turbo. With a turbo engine, the optimal exhaust is to have none after the turbo.
But that’s not really a practical plan for public transportation like street vehicles. Here is when the installation of a high-flow catted downpipe or a catless downpipe comes into play. They’ll free up more power in the Subaru WRX engine by lowering the pressure inside of it.
Catless vs High-Flow Catted Downpipes
By omitting the cat from the downpipe entirely, “catless DPs” are more flexible. Therefore, the best power, torque, and spool can be achieved with a catless Subaru WRX downpipe. There are a few drawbacks to catless downpipe choices, though. A WRX with uncatalyzed exhaust pipes is unlikely to pass emissions testing. In comparison to catted downpipes, they will make a slightly louder and stinkier noise.
We wouldn’t be put off too much by the minor differences in smell and noise. Most people are probably worried about emissions first and foremost. It seems like a catted downpipe would be the best option for you here. You should get a catless Subaru WRX downpipe if you’re not worried about emissions or are willing to switch back to a catted downpipe for emissions testing. Without a doubt, they provide the greatest value for the money.
High-flow DPs typically cost twice as much and deliver marginally less performance than standard DPs. While high-flow downpipes still include a catalytic converter, their enhanced design allows for greater movement of exhaust gases. In comparison to a catless downpipe, the output of a high-flow downpipe is typically lower due to the additional resistance encountered by the exhaust gas during its journey. In spite of this, they continue to be a fantastic option for those looking for more power without risking a violation of emissions regulations.
Subaru WRX Downpipe Pros
A few benefits to running upgraded downpipes on a VA WRX include:
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- 10-20whp (5-15whp w/ cats)
- Similar torque gains
- Quicker turbo spool
- Lower back-pressure & EGT’s
- Louder exhaust
It’s safe to say that the substantial performance benefits offered by downpipe enhancements for the Subaru WRX are the upgrades’ primary selling point. The aforementioned benefits are shared by both the catted and catless alternatives. But, in terms of overall performance, a catless downpipe will always be superior to a catted DP. With catless downpipes, you can get roughly 10–20 hp at the wheels. Gains could be increased with more modifications and fine-tuning. The WRX’s power improvements with a catted downpipe are roughly 5whp lower than with a catless system. Power and torque increases will be almost equivalent.
Again, the reduced back pressure brought on by the pressure decrease will speed up the turbo’s spooling process. This decrease in pressure aids in maintaining manageable exhaust gas temperatures (EGTs). In any case, there are obviously a ton of benefits to using an improved downpipe on the FA20 Subaru WRX.
Subaru WRX Catless DP Sounds
When customizing a Subaru WRX, the audio system is frequently a top priority. That’s mostly due to the fact that they have a fantastically distinctive factory sound. The FA20F flat-4 boxer engine found in the VA WRX is responsible for the car’s distinctive “Subaru rumble.” Better performance and a deeper, more gratifying rumble are both possible with a WRX downpipe upgrade.
In any case, removing the catalytic converter from a DP will make the WRX’s exhaust sound deeper and more ferocious. Noticable when first starting up or applying full speed. At a warm idle, the engine will not significantly deviate from its factory sound (assuming the rest of the WRX exhaust is stock). It is also difficult to pick up the DP noises while sailing along regularly. They provide a somewhat louder exhaust note without becoming excessively so.
An improved WRX cat-back exhaust combined with a catless downpipe will produce the loudest overall tone. When you put them together, the diameter of your exhaust system as a whole will be much greater, which will cause a resonant noise. This combination provides the greatest possible increase in power over the stock WRX exhaust. See our WRX Performance Exhaust article for more info on WRX exhaust systems.
VA Subaru WRX Upgraded Downpipe Options
Now that we have that out of the way, we can discuss some of the best downpipe modifications for the Subaru WRX. Various DPs, both with and without cats, will be detailed. It’s worth stressing that this is far from being an exhaustive list. There is a plethora of aftermarket WRX downpipe manufacturers. These are merely few examples of solutions we’ve found to be particularly advantageous in terms of cost-effectiveness.
1) Cobb Subaru GESi Catted 3″ Downpipe
If you own a 2008-2015 WRX and are in the market for a high-flow catted DP, Cobb is a fantastic choice. Cobb designed this downpipe to reduce the amount of exhaust turbulence at the turbo’s outlet and thus eliminate unnecessary backpressure. The Cobb GESi is impeccably built from the ground up with 304 stainless steel, making it both sturdy and resistant to rust and other forms of corrosion. As a result of its tried-and-true quality and reliability, the WRX community embraces it as an option.
The Cobb GESi 3″ Downpipe is battle-ready right out of the box. Turbocharger mounting bolts and studs are relieved of some of their burden thanks to a welded bracket that makes use of the factory hard mount close to the transmission. An extra-strong flange is built into the downpipe’s back end to withstand rough treatment during assembly. All you need are the gaskets, nuts, and studs that are included to attach it to your stock WRX cat-back.
The high-flow cat found in the Cobb GESi ensures significantly increased performance over the standard model. In contrast to a catless downpipe, this one won’t improve your vehicle’s performance. However, if you go with a catted variant, you should have much better luck with the emissions test. Note that this downpipe does not guarantee compliance with emissions standards in states with stricter requirements.
2) Tomei WRX Full Titanium Catless Downpipe
Tomei is well-known in the aftermarket for Subaru vehicles. Subaru aftermarket items have been consistently high quality thanks to their efforts over many years. The same can be said for their titanium catless downpipe. Tomei claims that the primary motivation behind developing their titanium downpipe was to provide the highest-quality component for maximizing both throttle responsiveness and mid-range horsepower.
To achieve this goal, they used a lightweight but strong material like titanium for the downpipe. Right out of the box, you’ll have everything you need to set up your Tomei. If you’re looking for a high-quality product at a reasonable price, the Tomei is likely your best bet.
3) GrimmSpeed Catted Downpipe
The Subaru aftermarket industry also includes the brand GrimmSpeed. GrimSpeed, much like Cobb and Tomei, is a reputable company selling anything from downpipes to boost controllers. The GrimmSpeed downpipe is built similarly to the Cobb described above. Each is made of 304 stainless steel, and there is only one catalytic converter in each exhaust system.
Aftermarket exhaust parts don’t always fit perfectly. It’s frustrating when a replacement component doesn’t fit in with the existing setup. Advanced 3D scanning technology was used in the design of the GrimmSpeed catted downpipe.
When comparing the Cobb and the Tomei, the GrimmSpeed Catted downpipe provides a good compromise between the two in terms of performance and cost. One of the least expensive catted WRX downpipes on the market, the GrimmSpeed costs only $839.
Subaru WRX Downpipe Upgrades Summary
Any turbo engine would benefit from upgraded downpipes. For the Subaru WRX, that is absolutely correct. Gains in output of around 10-20 whp can be had by switching to a downpipe without a catalytic converter. High-flow catted DPs will reduce power by around 5 hp. Faster turbo spool and an improved power curve are other benefits. Both catless and catted downpipes will make your WRX sound slightly deeper and more aggressive.
Tomei’s Full Titanium catless downpipe is an excellent choice for anyone in search of a catless system due to its affordable price, high quality, and excellent performance. Check out Cobb’s catted downpipe if you’re concerned about exhaust fumes. Nameless, Invidia, and many others provide competitive options, but at far higher prices. You can’t go wrong with any of the available Subaru WRX downpipe improvements.
