Downpipes are one of the best performance upgrades for turbo engines. There are tons of benefits to running a downpipe upgrade on a Subaru WRX. Downpipes are one of the most important exhaust components for force-induced engines, as they are the first exhaust component after the turbo. They are a part that can either throttle an engine’s performance or increase performance dramatically.
A Stock WRX downpipe features a restrictive cat which is good from an emissions standpoint but not so good from a performance standpoint. Luckily, there are plenty of upgraded WRX downpipes out there with different configurations to suit your needs. In this guide, we’ll compare catless vs catted downpipes and discuss a few of the best downpipe mods for the Subaru WRX.
*Note – this article is relevant to 2008-2021 Subaru WRXs.
Subaru WRX Downpipe Performance
The catalytic converter (cat) in the OEM WRX downpipe helps reduce emissions. It does a great job at that. Unfortunately, the cats are also highly restrictive and hurt power and performance. The pressure drop from pre to post-turbo plays a big role in a turbo’s ability to spool. As such, reducing back-pressure after the turbo allows for a quicker spool and more power. No exhaust after the turbo is actually the best exhaust on a turbo engine.
However, that’s not exactly a realistic proposal for street cars. That’s where catless and high-flow catted downpipe upgrades come into play. They will help reduce the Subaru WRX engine’s back pressure and free up horsepower.
Catless vs High-Flow Catted Downpipes
Catless DP’s are less restrictive as they completely remove the cat from the downpipe. As such, a catless Subaru WRX downpipe will result in the best power, torque, and spool. However, catless downpipe options come with a couple of downsides. A WRX with catless downpipes won’t likely pass emissions. They’ll also add a bit more sound and smell compared to catted downpipes.
The smell and sound differences are pretty minimal, so we wouldn’t let that scare us away. Emissions are likely the primary concern for most. In this case, you’ll likely be best suited to a catted downpipe. If you aren’t concerned with emissions or are willing to swap back to a catted downpipe for emissions testing, we highly recommend opting for a catless downpipe. They offer the best bang for the buck without question.
High-flow DP’s are often about twice the price and offer slightly less performance. High-flow downpipes retain a catalytic converter but feature a better design which improves exhaust gas flow. Generally speaking, high-flow downpipes will yield less power than a catless downpipe because exhaust gas still has to travel through an additional component. However, they remain a great choice for those who want some more power without possibly breaking emissions laws.
Subaru WRX Downpipe Pros
- 10-20whp (5-15whp w/ cats)
- Similar torque gains
- Quicker turbo spool
- Lower back-pressure & EGT’s
- Louder exhaust
Big power gains are likely the biggest selling point of downpipe upgrades for the Subaru WRX. Both catted and catless options will provide the same pros above. Though, a catless downpipe will out-perform a catted DP in all areas. Expect to pick up around 10-20 wheel horsepower with catless downpipes. Higher gains may be possible depending on other mods and tuning. Regardless, power gains with a catted downpipe will be about 5whp less than catless. Torque gains will be about the same as power.
Again, the drop in pressure will also help the turbo spool faster due to the lower back pressure. That reduction in pressure also helps keep exhaust gas temps (EGT’s) lower. All that said, there are clearly tons of advantages to running an upgraded downpipe.
Catless DP Sounds
Sound is oftentimes one of the most important elements of modifying a Subaru WRX. That’s largely because of their extremely unique sound from the factory. The VA WRX features a FA20F flat-4 boxer engine that produces the signature “Subaru rumble” due to its configuration. An upgraded downpipe can enhance the satisfying rumble while simultaneously providing decent performance gains.
Anyways, a catless DP will definitely add a deeper, more aggressive note to a WRXs exhaust. It’s mainly noticeable on a cold start or under heavy throttle. Once the engine is warm the idle will sound pretty similar to stock (assuming the rest of the exhaust is stock). Additionally, while cruising normally the DP sounds are hard to detect. Point is – they offer a bit of a louder exhaust note without becoming annoyingly loud or intrusive.
For the most pronounced overall sound, your best bet is a catless downpipe with an upgraded cat-back exhaust. In combination, the overall diameter of your exhaust system will likely be significantly larger, which will resonate noise. Power gains from this combo are the best that you can get from a WRX exhaust system. If you are interested in learning more about WRX exhaust options, check out our WRX Performance Exhaust article.
*Sticking with the theme, high-flow DP’s are louder than stock but to less of an extent than catless.
Upgraded Downpipe Options
With all that out of the way, let’s move on to a few of our favorite Subaru WRX downpipe upgrades. We’ll list some catless and catted DP options. It’s important to note – this is by no means an exhaustive list. Tons of companies make aftermarket downpipes for the WRX. These are simply a few that we believe offer the best balance of price, quality, and performance.
- 1) Cobb Subaru GESi Catted 3″ Downpipe
- 2) Tomei WRX Full Titanium Catless Downpipe
- 3) GrimmSpeed Catted Downpipe
Our Top Pick – Cobb Subaru GESi Catted 3″ Downpipe
Buy Here: Cobbtuning.com
Cobb offers a great option for 2008-2015 WRX owners looking for a high-flow catted DP. Cobb’s goal with this downpipe is to minimize exhaust turbulence coming out of the turbo, preventing excess backpressure. The Cobb GESi is made entirely out of 304 stainless steel, meaning that it extremely strong and corrosion-resistant. It is a popular choice in the WRX community with proven quality and performance.
Out of the box, the Cobb GESi 3” Downpipe is ready to rumble. A welded bracket utilizes the factory hard mount near the transmission reducing stress on the turbocharger mounting bolts and studs. The rear of the downpipe features a heavy-duty flange that can withstand some abuse during installation. It can be bolted up to the factory WRX cat-back using the included gaskets, bolts and studs.
Since the Cobb GESi features a high-flow cat, performance is unquestionably much better than stock. However, it won’t give you the same performance benefits as a catless downpipe. With that being said, a catted option will give you a much better chance at passing emissions. It is important to note that if you live in a state with strict emissions regulations, there is no guarantee that you will pass with this downpipe.
Subaru WRX Downpipe Upgrades Summary
Upgraded downpipes are an excellent mod for just about any turbo engine. That holds true for the Subaru WRX. A catless downpipe offers power gains in the ballpark of 10-20whp. Expect about 5 horsepower less with high-flow catted DP’s. You’ll also notice quicker turbo spool and a better all-around power curve. Additionally, catless and catted downpipes will add a slightly deeper, more aggressive note to your WRX.
Those looking for a catless downpipe will enjoy the great price, quality, and performance from the Tomei Full Titanium catless downpipe. If you’re concerned with emissions, check out the catted downpipe option from Cobb as well. Nameless, Invidia, and tons of other companies have some solid choices as well but they are quite a bit pricier. Regardless of your choice, it’s hard to go wrong with Subaru WRX downpipe upgrades.
What’s your experience with WRX DP’s? Are you considering one?
Drop a comment and let us know! As always, safe driving!