Catless Vs Catted Downpipe – Know the Detail Explanation in 2023!

Understanding the difference between a catless vs catted downpipe is crucial for those who want to install a downpipe but don’t know which one should install.

To put it straight and simple, a catted downpipe is preferable on public roads to a catless downpipe, especially if the vehicle is used frequently.

Even catted downpipes have roughly 5-10 fewer horsepower.

They offer many more advantages over the catless variant, including much lower emissions, no foul odors, and a reduced risk of the check engine light coming on (CEL).

Subaru Catless vs Catted Downpipe: Face to Face Comparisons

What is a Downpipe?

A downpipe’s job is to send a vehicle’s turbine housing exhaust gases into the Subaru exhaust system. The downspout is attached directly to the turbine housing.

Thus, it plays a crucial role in the effective passage of exhaust gases through the system.

A downpipe improves the performance of the engine’s turbocharger. It directs exhaust gases away from the turbine, resulting in increased output with less interruption.

However, a user can notice the difference when they step out of their Mercedes or comparable vehicle and open the door straight away.

Many automobile owners who wish to make the most of their vehicle’s power potential install a non-factory downpipe to improve performance.

Types of Downpipes

The following are the different types of downpipes:

  • Simple pipe flange

This design’s only benefits are its simplicity and low cost. There is no need to shape the pipe, and the flange is simple.

In addition, welding the pipe to the flange is a low-cost and straightforward process.

  • Bellmouth

This is the best way to connect the gases coming from the outlets. In terms of packaging and intricacy, it’s really good.

  • Split Bellmouth

Gases are separated in a bell mouth part for this design and later rejoined in the turbo outlet.

It works effectively and combines some of the best features of both bell mouth and detached wastegate designs in one package.

  • Divorced Wastegate

For seamless pipe joining and minimal turbulence, it ensures power production and spool-up.

  • Cast outlets

The advantage of castings is that they hold a lot of heat in the exhaust and provide a lot of design freedom.

So, one will have a lot of creative freedom with this one as far as shapes are concerned.

  • Formed Piping

Compared to casting, formed pipe offers almost as much design freedom but at a lower cost and generally lower weight.

Catless Downpipe

Hardcore racers will opt for an utterly catless downpipe. If a user wants the best performance improvement with the slightest noise, this is the best bet.

In addition, there are no airflow constraints with a catless downpipe because it does not have a catalytic converter.

Keep in mind that catless downpipes emit a foul odor and are therefore not permitted (it depends on the region where one is living in the US).

Catless downpipes reduce backpressure and speed up turbocharging by reducing the adverse effects of having an exhaust system after the turbo.

Boost pressure rises due to the increased speed of the air as it approaches the turbine, increasing power.


Here are some of the essential aspects that one can find in the catless downpipes:

  • Boosts horsepower

Catless downpipes can increase the horsepower by 25 without tuning or by 50 once a user tunes them.

Utilizing a catless downpipe (aftermarket) generally results in an increase of 15 to 20% in horsepower. The more power a user gets from an engine and turbo, the better.

On a 2016 Civic, after installing a catted downpipe and having it tuned, a few users have found an increase of roughly forty horsepower on the dyno.

With a catless downpipe, the power should be roughly 20%-30% higher; this is a reasonable estimate from our perspective.

Whether it’s catted or not, a downpipe is, in our opinion, the most worthwhile aftermarket upgrade. Headers, exhausts, and an intake system follow.

  • Weight reduction

One of the essential features of an aftermarket catless downpipe is that it’s pretty lightweight. As a result, it becomes very convenient for a user.

  • Sound is improved

A catless downpipe ensures that users get optimum sound boosts for their engine, which is an added advantage.

  • Stylish

Catless downpipes come with an advanced design which also enhances their style.

Important Features

  • Boosts throttle response and turbo spool up
  • It puts lesser pressure on the turbocharger
  • Offers direct replacement (bolt-on)
  • They’re made with high-quality steel

Catted Downpipe

Option two for a downpipe is a performance catted downpipe designed to move more air at a higher flow rate.

The cells for every square inch are more minor, even though the catalytic converter will exist. To put it another way, the downpipe will provide more airflow than the factory one.

Catted downpipes, on the other hand, cost more than cat-free ones. The platinum and palladium in the catalytic converter will raise the price.


Let’s now have a closure look at some of the value additions that a catted downpipe can bring:

  • Horsepower boost

All-in-one exhaust systems can enhance horsepower, but the increase isn’t as large as stated because newer catalytic converters aren’t overly restrictive.

  • Complies with emission laws

This is the best option if the state where the user lives has strict emissions standards and wants to meet those criteria while still getting a large flow.

  • Environmental-friendly

When an automobile’s exhaust is being processed, it passes through a catalytic converter (CAT).

As a result, some substances like carbon monoxide (CO) are transformed into carbon dioxide (CO2) to keep the driver and the environment safe.

  • Works well with different vehicle mods

A catless downpipe will help to boost the air intake system of a vehicle. They help in better exhaust flow as well, which is essential in better performance of the engine.

Important Features

  • It’s compatible with the OEM exhaust or a 3.00″ exhaust pipe
  • It features a laser-cut turbo flange,
  • Extra O2 bung for attaching a wideband sensor
  • High-flow metallic honeycomb cat in the metallic finish (optional)
  • comes with a laser-cut stainless steel bracket
  • Flex joint made of stainless steel, the best in the business
  • 304-grade stainless steel full mandrel bent (3.00″)
  • Titan treatment to strengthen the material and offer a clean, uniform finish
  • Smart O2 Simulator with Off-Road Downpipe included
  • Over 5% increases in upper RPMs
  • Made in the United States of America.

Price Ranges for Catted VS Catless Downpipe

Catless Downpipe Price

The catless one is lower-priced since it does not come with a catalytic converter than a catted downpipe.

Usually, the price starts with around $150, and then there are prices above that as well, depending upon the quality of the model and design.

  • BMW Catless Downpipe

A TIG Welded, entirely stainless-steel made (304-grade) 335/135 catless downpipe will cost around USD 650.

  • BMW X1 Catless Downpipe (3.5”)

Such a Catless Downpipe is also made with 304-grade supreme quality stainless steel that can be obtained at $350. These pipes are TIG-welded as well and won’t require any tuning.

  • Fiesta ST 2014 Downpipe (3”)

This brand of catless downpipe is a direct replacement item. Such a downpipe is also known to maximize exhaust flow and deliver over ten hp gain without being tuned.

Such a downpipe with a 3” machined flange and an elbow section of 3.5” is available at $386.

Catted Downpipe Price

A catted downpipe costs more than a catless downpipe since it requires an additional aftermarket CAT. Around $350 and above is the price range for a catted downpipe.

Here we go with the price range of some of the top catted downpipes so that a user can have an idea:

Price Ranges

  • Mustang EcoBoost 2.3L (2015) 3″– The price it will be available at will be $399
  • Mazdaspeed3 Downpipe (07-14) 3″ Ver3– The cost of this downpipe will be $395.00
  • WRX/STi (02-07) 3″ Downpipe– It will cost $325.00 USD
  • BMW 335/135 Catted Downpipes (High-Flow) ((RHD Model)- The price is on the higher side at $950.00

Note:  Some of these downpipes are available in both catless and catted versions.

Catted or Catless Downpipes: Pros and Cons

Are you still in confusion as to what downpipe to go for? Here is a brief analysis of the pros and cons of both catless and catted downpipes:


Although the emissions from a catted downpipe are harsher than those from a stock downpipe, they are still much lower than those from a catless downpipe.

The emissions from a catless downpipe are atrocious. As a result, this downpipe must be swapped out before taking an emissions test to pass it.


There is less of a power boost with a catted downpipe than with a catless one. Catless downpipe offers even more significant gains in horsepower than catted downpipe.

Going catless has several benefits, but the biggest is improved performance.

Enhanced Sound

Both Downpipes will both improve sound quality. However, the catless one produces a louder sound than those with cats.


A catted downpipe emits a faint odor from the exhaust when driving with the windows open. There is a strong exhaust fume smell when using a downpipe with no catalytic converter.


Every day driving should be possible with the catted downpipe. It improves performance while also reducing emissions, noise, and odor.

An automobile with a catless downpipe is unusable regularly.

When every bit of performance counts and emissions aren’t as crucial in off-roading or tracking, these are better suited to the job.

Is tuning needed?

After adding any downpipe, whether catted or not, one should tune their automobile for maximum performance.

After installing a performance upgrade, one can boost the car’s horsepower by tuning it.


Catted and catless downpipes are both illegal on public roads. They’re solely available for off-roading and tracking.

However, traffic enforcers won’t see a catted downpipe if anyone utilizes it, so they won’t have to worry.

Will my warranty be voided?

The warranty should not be voided if aftermarket downpipes are installed. Due to the Magnusson-Moss Warranty Act, a user is covered.

In addition, according to federal law, the manufacturer cannot deny warranty coverage if one utilizes an aftermarket item.

Front pipe vs. downpipe

What’s the difference between a front- and a down-pipe? Where do they diverge? Let’s check:

The connecting point

The Front pipe links the turbo to the exhaust manifold. The front pipe is where exhaust fumes are brought into the turbo.

An exhaust system’s down-pipe connects the turbocharger to the remainder of the exhaust system. The down-pipe sends exhaust gases to the turbocharger.

Exhaust flow

The exhaust manifold is connected with the turbocharger by the front pipe, which allows exhaust gases to flow in both directions.

Down-piping then allows turbocharged exhaust gases to escape and enter the exhaust pipe.

Catalytic converters

Catalytic converters are included in the front and down-pipe and allow exhaust gases to pass (CAT). CAT is in charge of transforming hazardous exhaust gases into a safer form.

Aftermarket front and down-pipes ensure an exhaust system’s unrestricted flow, enabling the turbo to take in more air and feed more fuel to the combustion chamber, resulting in higher horsepower.

Important FAQs for the Catted vs Catless Downpipe

How does a downpipe work?

A downpipe is a component found in automobiles. Once the exhaust manifold is connected, it sends exhaust gases to the catalytic converter, cleaned up by an aftermarket exhaust system.

Does installing a downpipe increase the volume of a car?

Adding an aftermarket downpipe definitely increases the volume and aggression of a vehicle’s sound.

Is it bad to have a catless downpipe?

A catless downpipe is not only harmful to the environment; it’s bad for a user, bad for their community, and for the engine too. Besides, it doesn’t produce any significant extra power.

Why it’s illegal to use downpipes?

Due to severe pollution concerns, operating a car with a catless downpipe on public roads is unlawful.

However, a catted downpipe is the best option if users install a downpipe on their everyday driving. It’s less powerful, but it’s still legal, and it’ll pass emissions tests if they buy it.

What’s louder, Catted or Catless?

Do catless headers sound any louder when compared to catted ones? Both are a lot more audible.

Most headers’ high-flow cats don’t add much loudness, but they do reduce rasp.


While researching on catless vs catted downpipe, all these points do matter.

Whether someone is a serious track racer or a weekend warrior tuner, an aftermarket downpipe can be an excellent addition to their vehicle.

Always analyze the advantages and disadvantages of the catted and non-catted versions before making a decision.

A catless downpipe is the best option for those who don’t mind the stench and want the best performance.

Eventually, a catted downpipe is the ideal choice if someone doesn’t want to disturb their neighbors every time they start their automobile.