What is a Downpipe and Why You Need One

What is a Downpipe and Why You Need One

June 13, 2020

What is a Downpipe and Why You Need One

If you know anything about car exhaust system parts, then you might be familiar with downpipes. However, plenty of car owners have never considered this part of a vehicle. Let’s examine what a downpipe does, and why it’s such a vital aspect of your exhaust system, particularly if you own a high-end sports car.

Downpipe Basics

A downpipe directs the exhaust gases from your vehicle's turbine housing into your exhaust system. The downpipe bolts right to the turbine housing. It is instrumental in moving the exhaust gases through the system as efficiently as possible.  

The average downpipe has at least one restrictive catalytic converter. These do an excellent job of cleaning exhaust gases as they are produced. The only issue is their restrictive aspect. They cause you to lose power, and likely part of the reason you’re buying a high-end car like a Mercedes is the power that comes with it.

Another aspect of the typical sports car exhaust system that you’ll likely notice is mandrel bending. This is where a steel rod is inserted into bent tubing, so there is no wrinkling or breaking at the bend point.  

Should You Keep the Downpipe that Comes with Your Vehicle?

Let’s say you get yourself a high-end, supercharged vehicle, like a Mercedes. You’re probably serious about testing its limits when you drive it. If that’s true, you might look into purchasing an aftermarket downpipe replacement.

Mercedes exhausts that are standard-issue are already considered to be high-performance quality. However, you probably didn’t buy the Mercedes to be timid.

That’s why you might want to remove the original downpipe that came with your Mercedes and replace it with an aftermarket version larger in diameter. You also might remove the catalytic converter, or another way to go is to install a high-flowing converter.

Why You Need a Downpipe

A downpipe is put in place because it allows the turbo aspect of the engine to be more effective. The downpipe steers gases away from the turbine, creating more uninterrupted power. When you get out on a straightaway and open up your Mercedes, or a similar vehicle, you’ll feel the difference.

Aftermarket downpipes usually feature wider capacities, and they are less restrictive than the stock option. This increase in diameter allows for greater space for a faster turbo spin.

The increased spin makes a huge difference. It decreases turbo lag and generates more spool. When you make this switch, you’re reducing intake charge and engine temperature. This will bring the increase in engine power you were craving. 

A non-factory issue downpipe significantly increases enjoyment for many car owners who want to fully appreciate the vehicle’s power potential.  

The Difference Between Cat vs. Catless 

If you want to get yourself an aftermarket downpipe, you’re going to run into two kinds: cat and catless. Catted means that it comes with a high-flow catalytic converter. Catless downpipes come without one.

Catalytic converters clean exhaust gases as they pass through a catalyst. This deals with the smell from the raw exhaust fumes. If you get a catless version, then the vehicle will emit a noticeable odor. That’s because the exhaust gases aren’t being cleaned before the vehicle emits them.

You probably don’t want the smell that comes with a catless converter, which is why many sports car owners opt for the catless variety. 

Buying a New Downpipe

If you aspire to race your sports car, that is one of the more common reasons for replacing the downpipe. You might choose to do so simply because you are trying to get as much horsepower as possible out of your vehicle. Adding a new downpipe to older model sports cars can dramatically improve your HP.  

There is another potential reason. You might have modified your turbo so that it runs at a higher boost pressure. If you have increased the amount of boost from a stock turbo system, then the increased exhaust output might demand a smooth, larger downpipe.

Keep in mind that the standard downpipe for sports cars is typically of excellent quality. It’s entirely your prerogative whether you’re satisfied with your exhaust materials or want to modify them further to get that extra boost.