Recently, I have been looking into up-pipes and downpipes. Asked my petrolhead friends what these are and what makes them different. I would often get the response, “buddy, these pipes are not a big deal. They’re all the same.”
Well, guess what I found after thorough research? These pipes are actually A BIG DEAL, and they do have some differences!
An up-pipe is a component of the exhaust system connecting the turbo to the exhaust manifold. On the other hand, the downpipe connects the remaining exhaust pipes to the turbo.
Though people may claim that they are both the same thing, it is very UNTRUE. I will talk about the major differences in the article as well as explain why the pipes are loved by enthusiasts.
Let’s jump right into it!
Comparison Table Between Up-Pipe Vs Down-Pipe
|Definition||The up-pipe let the gas flow through it into the turbo from the exhaust manifold.||Downpipes let the gas leave the turbo and flow into other exhaust pipes.|
|Focuses on||Providing slightly more horsepower when the engine runs at low RPM.||Offering a massive gain in horsepower regardless of the RPM level.|
|Effect on the Vehicle||Up-pipes enhance aggression and responsiveness of the car.||The downpipe has no major impact on your riding experience since it only affects horsepower.|
|Horsepower Increase||Approximately 10-15 more hp.||Around 20-25 more hp.|
|Cost||More expensive.||More budget-friendly.|
What is a Turbocharger?
The turbocharger often referred to as ‘turbo,’ goes hand in hand with the up-pipes and downpipes. It is impossible to install a turbo on a car without these pipes.
Okay, but what exactly is a turbocharger, and why do you need it?
Turbochargers are arguably the best way to raise the horsepower of a vehicle. It can boost the hp by 10-50%, meaning the vehicle can generate up to 120 extra horsepower with this component.
It seems unbelievable, right? It won’t be as unbelievable once you realize how the turbo generates so much power. So let’s talk about that.
The combustion chamber is where the horsepower is produced. The more combustion there is, the more power your car will generate. It is important to remember that combustion also emits toxic gasses.
To produce more combustion, you need more explosions of it, which you can achieve with fuel and air. You can supply as much fuel as needed, but how are you supposed to provide more air?
This is where turbos come into play. Essentially, it operates like an air compressor through the rotation of a turbine.
As the toxic gas released by combustion starts flowing, it powers the turbo by causing the turbine to spin very fast. Now that the turbo has begun functioning, it will draw in the surrounding air, compress it, and discharge the air into the combustion chamber.
In this way, a turbocharger contributes to a massive boost in horsepower.
Now that you know about turbos, up-pipe and downpipe should be easy to understand.
Let’s go over them.
As you already know, aside from producing power, combustion generates gas, otherwise known as exhaust gas. This gas is what drives the turbine of the turbo.
However, to enter the turbo, the exhaust gas must leave the combustion chamber via the exhaust manifold. It passes through the up-pipe afterward and is sent to the turbo, where it spins the turbine.
As far as you are aware, the gas enters the turbo using the up-pipe, right? But does it exit the pipe or remain there? Well, the gas indeed exits, and it does so through the downpipe to the remainder of the exhaust pipes.
After flowing through the other pipes, the gas finally says goodbye to the car and makes its way outside.
Aftermarket Up-pipes and Downpipes: Why You Should Use Them
A closer look at stock up-pipes and downpipes reveals their confined and restrictive construction. When exhaust gas passes through such narrow channels, it is often obstructed.
Hence, it cannot play a major role in supplying the turbo with an adequate amount of power.
In comparison to the stock ones, the aftermarket up-pipes and downpipes are much wider. There are also fewer bends on these products.
Moreover, high-end up-pipes and downpipes boast catalytic converters that are known for their high flow rate.
All of this leads to the gas flowing more smoothly and spinning the turbine faster, ultimately making the vehicle more powerful.
When to Modify Up-pipes?
As I mentioned earlier, an up-pipe is the entry point for exhaust gas. As a result, you cannot expect the highest hp boost from it. However, up-pipes are still a great choice when you need more horsepower at a low RPM, e.g., 2000 – 3000.
An untuned up-pipe delivers about 10-15 extra hp. Despite the lack of a significant power gain, the car will feel aggressive and responsive because of the low RPM horsepower increase.
Read Also: Do Test Pipes Add Horsepower? (Should They Be Tuned?)
When to Modify Downpipes?
Not everyone enjoys a mere 10 hp being added to a car. In that case, the downpipes are the way to go as they can easily produce 20-25 horsepower—and that is without any tuning!
If you are a motorhead who only cares about power and not about the responsiveness of your vehicle, there is no better alternative to a downpipe.
Things to Consider while Modifying a Pipe
Consider the following factors before you modify the up-pipe/downpipe.
1. Replacing Both Pipes
In case you are not aware, both up and down pipes need to be removed even if you intend to modify only a single pipe. Thus, it is better to replace both of them with aftermarket ones if you have the budget.
2. Prioritizing Up-pipe
Unfortunately, the cost of replacing both pipes can exceed many folks’ budgets. Under that circumstance, my recommendation would be to modify the up-pipe only. Although downpipes increase hp, up-pipes make the car overall responsive.
3. Picking the Catted Pipe
When buying a pipe, you will come across two options: catted and catless. If your car severely lacks horsepower, you may want to go with the catless variant.
Having said that, catless pipes can cause a variety of problems, including bad odors, check engine warnings, and environmental damage.
Based on these factors, I would advise my readers to go for the catted pipes.
Should You Tune the Up-pipe and Downpipe?
Even though tuning is expensive, it is well worth it when you want to maximize your pipe’s performance.
A tuned up-pipe will produce around 30 hp, while tuned downpipes deliver nearly 50 hp, as opposed to their untuned outputs of 15 and 25 horsepower.
Aside from enhancing performance, tuning gives you the freedom to customize the pipe to your liking. You will no longer encounter check engine warnings and a few other issues if you adjust the pipe correctly.
Effects of the Up-pipe and Down-pipe on Sound
As long as the up-pipe and downpipe come from an aftermarket manufacturer, they will definitely enhance the sound of an exhaust system. More importantly, the sound will be loud enough to be noticeable but not obtrusive.
Some pipes, like straight pipes, also change the sound, but they can sometimes be really loud. Compared to that, the aftermarket up-pipe and downpipe will be quieter and produce a satisfying deeper tone with a bit of aggression.
Are Up-pipes and Downpipes Legal?
Aftermarket up-pipes and downpipes are exclusively made for racing and off-roading cars and trucks. As a result, you cannot legally use either pipe for daily driving.
However, if you are outside California, you are less likely to be caught since other states do not check your car as thoroughly.
Several cars are on the road every day with these pipes. Their owners are not facing any legal issues, so why should you be concerned?
Related: Is Straight Pipe Legal?
Are these Pipes Worth Installing?
Motor enthusiasts who have turbochargers in their cars should not miss out on installing the up-pipe and downpipe. The way they improve the sound, give a power boost, and enhance the car’s overall feel is worth every penny.
The results can be even better if you buy catted pipes and tune them to perfection.
In case you made up your mind and plan on buying the up-pipe or downpipe, take a look at our recommendations. We hand-picked the two following products based on their performance, sound, and build quality.
Dorman 679-005 Turbocharger Up Pipe
KIMISS 3in Steel V-Band to V Band Downpipe
I hope the article clarifies your questions about up-pipes and downpipes and shows how they differ while being almost equally important. Especially for turbocharged vehicles, the aftermarket pipes are a must-have for their roles in optimizing performance and sound.
If you like this article, you might also be interested in my other article about whether test pipes could replace cats.