FK8 Honda Civic Type R Downpipe Upgrade Guide

The FK8 Type R is the top dog in Honda’s Civic lineup with a heavy emphasis on track performance and peak efficiency. The Type R has defined the affordable FWD Japanese sports car segment for 25 years now and the FK8 is arguably the best generation yet. It looks good, it handles well, the 6-speed gearbox is a dream, and it makes plenty of turbocharged power. 

One of the best performance upgrades for the FK8 is an upgraded downpipe. 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. The stock Type R downpipe actually has a rather poor design, so there is a lot of power to be unlocked through high-flow or catless downpipe options. In this guide, we’ll cover the benefits of upgrading your FK8’s downpipe and recommend a few.

FK8 Civic Type R Downpipe Performance

The catalytic converter (cat) in the OEM Type R downpipe helps reduce emissions. It does a great job at that. As a trade-off, catalytic converters tend to be 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. In an ideal world, no exhaust after the turbo would actually provide the best performance 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 help reduce the K20C1’s back pressure and free up horsepower.

Catless Downpipe

Catless DP’s are less restrictive as they completely remove the cat from the downpipe. As such, a catless downpipe will result in the best power, torque, and spool. However, catless downpipe options come with a couple of downsides. A Civic Type R 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 usually tolerable, so don’t let those two factors scare you away. Emissions are likely the primary concern for most. If you don’t want to worry about that hassle,  a catted downpipe is the way to go. If you aren’t concerned with emissions or are willing to swap back to the factory downpipe for emissions testing, we highly recommend opting for a catless downpipe. They offer the best bang for the buck without question. 

With that being said, new catless Type R downpipes are hard to come by these days. Most of the most prominent Honda aftermarket manufacturers have discontinued production of catless downpipes due to stricter EPA regulations. For that reason, you might have to source one from a secondhand seller.

High Flow Downpipe

High-flow catted Type R DP’s are often the more costly option 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. 

While they might generate a less significant performance gain, high-flow downpipes remove some of the hassle associated with going catless. For example, you’ll be able to pass emissions without the need to swap in a different downpipe every time you need to test. They are also the best choice for those who don’t want the additional exhaust drone or pronounced turbo noise (although, why would that be the case?). High-flow downpipes also tend to emanate less smell as well, as most of that is captured within the catalyst like with the stock downpipe.

Downpipe Tuning Considerations

It is very important to remember that most of the power gains from an upgraded downpipe don’t necessarily come from the downpipe itself. In fact, tuning is an extremely vital component when upgrading your FK8 Type R downpipe for a number of reasons. The first reason is that the engine’s ECU needs to be programmed to be able to recognize the increase in airflow. Without the engine recognizing that the downpipe has been changed to a less restrictive one, you might not see a power increase at all. 

The second reason is that without a tune, replacing the factory downpipe can trip a check engine light. The FK8 Type R is actually a pretty finicky vehicle when it comes to exhaust/downpipe-related modifications. Some owners claim that even some catted downpipe options can even trigger a CEL without proper tuning. 

While most aftermarket downpipe options come with an O2 sensor bung, the factory sensor is looking for a specific reading based on the airflow figures from the factory downpipe. When you change the airflow characteristics of the downpipe, the O2 sensor receives a different reading and triggers an error. This problem can either be fixed through tuning or by installing a defouler.

Downpipe Pros

• 15-30whp (10-20whp w/ high-flow 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 FK8 Type R. Both catted and catless options will provide the same pros above. However, catless downpipes outperform catted DPs in all areas. Expect to pick up around 15-30 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 5-10whp 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 (EGTs) lower. Overall, the individual benefits of an upgraded downpipe really add up. Speaking from strictly a performance standpoint, there are few modifications in the same price point that can yield as much power. 

Upgraded Downpipe Sound

This one tends to be a polarizing subject for some people. One of the most prominent changes in daily drivability with an upgraded downpipe is the extra noise that it produces. Since you are effectively increasing the diameter and flow rate of one of the most crucial exhaust components, an upgraded downpipe will almost always make your car louder. For most enthusiasts, that is a definite pro. However, if you daily drive your Type R and don’t want to deal with more noise in the cabin, it might not be ideal.

For those looking for improved sound, a catless or high-flow downpipe will definitely serve you well. Pretty much every sound that enthusiasts typically want to hear will be enhanced with a performance downpipe. Owners running an upgraded downpipe commonly report that their car produces a more noticeable bass tone within the cabin and louder turbo induction sounds when jabbing the throttle. Obviously, the sound difference will be more significant with a catless downpipe. Catless Type R downpipes also pronounce more crackles and pops from the K20C1, which can definitely be fun. 

As a general rule of thumb, if you aren’t crazy about the idea of your Civic being louder both inside and outside of the cabin, stick with a high-flow catted downpipe. If you are on board for some additional turbo and induction noise, a catless downpipe is the way to go.

FK8 Honda Civic Type R Upgraded Downpipe Options

With all that out of the way, let’s move on to a few of our favorite downpipe upgrade options. 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 FK8. These are simply a few that we believe offer the best balance of price, quality, and performance.

• 1) PRL Motorsports High Volume Downpipe Upgrade
• 2) RV6 Catless Civic Type R Downpipe Upgrade
• 3) MAPerformance FK8 Civic Type R Downpipe

Our Top Pick – PRL Motorsports High Volume Downpipe Upgrade

When researching the topic of best Type R downpipes, you’ll see PRL’s name pop up very consistently among FK8 owners and the entire Honda tuning community at large. There’s a very good reason for that. Since 2007, PRL Motorsports has been dedicated to providing the Honda aftermarket community with the highest quality parts at reasonable prices. The same can be said for their high volume catted downpipe for the FK8 Type R.

One of the most important standout features of the PRL downpipe is their decision to implement an extremely large 5.0” GESI G-Sport high-flow catalytic converter in the middle of the downpipe. Other manufacturers tend to go with a smaller diameter cat, in line with the diameter of the rest of the piping, which can restrict flow more than what is necessary. The large cat design not only provides the best flow numbers for a catted downpipe but also causes less internal turbulence. 

In terms of the PRL Type R downpipe’s actual shape and construction, it is constructed entirely out of 304 stainless steel and shaped to provide the least resistance for gas flow. The revised shape of the PRL downpipe is perhaps its most important characteristic as far as performance is concerned. The wide inlet smoothly blends the turbine outlet and wastegate gasses to reduce restrictions. The outlet is also less sharply angled than the factory downpipe which allows exhaust gasses to escape more easily.

Price: $950.00

FK8 Downpipe Upgrades Summary

Upgraded downpipes are an excellent mod for just about any turbo engine. That holds true for the Civic Type R. 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 Civic.

Those looking for a catless downpipe will enjoy the great price, quality, and performance from the RV6 catless downpipe. If you’re concerned with emissions, check out the catted downpipe option from PRL as well. MAPerformance, Skunk2, 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 a Civic Type R downpipe upgrade. As always, safe driving!