Customizing your exhaust system from headers to tailpipe ensures you get the sound and performance you're looking for. One of the most important exhaust pieces you'll need to decide on is the mid-pipe.
What Is a Mid-Pipe?
The mid-pipe is the section of exhaust that runs between the muffler and the catalytic converter. Some mid-pipes will have the catalytic converter built in. When you’re upgrading the rest of your exhaust, you’ll need to decide what type of mid-pipe will fit your build.
Do You Even Need a Mid-Pipe?
As your engine runs, the cylinders fire at different times. This creates waves of pulsating exhaust. A mid-pipe equalizes your exhaust, creating a more consistent flow.
You can have an exhaust without a mid-pipe. But considering they offer performance and sound benefits, most people opt to have one.
Types of Mid-Pipes
Mid-pipes come in several styles. Whether your vehicle is single or dual exhaust will inform what exhaust pipe choices you have. While all single exhaust systems are Y-pipes, dual exhaust systems have a couple options.
If you have a single-exit exhaust, then you have a Y-pipe.
Y-pipes take two exhaust streams from the manifolds and join them together. Then as a single pipe, the gas travels through the muffler and exits through one tailpipe.
The obvious con of this system is that it’s restrictive due to the single pipe.
If you like having a single exhaust but want a less restrictive option, there are aftermarket Y-pipes. By increasing the diameter of the exhaust, these can improve your overall flow. Some of these Y-pipes also eliminate the resonator for a noticeable sound improvement. Eliminating the resonator also reduces your total weight, another benefit.
Single exhaust system
Can eliminate resonator for better sound
H-pipes take two pipes coming from the manifold and connect them with a small pipe, making an “H” shape. This design creates a deep muscle-car exhaust note and low-end torque.
H-pipes are able to offer more low-end torque by creating some backpressure. While generally you want to reduce backpressure to free up horsepower, a small amount can actually improve low-end torque.
Deep, throaty exhaust sound
Slightly less free-flowing than an X-pipe
Small increase in low-end torque
X-pipes are the freest flowing option for a mid-pipe. Instead of having a crossbar, like the H-pipe, the X-pipe takes two pipes and crosses them over. Sometimes X-pipes are called crossover pipes for this reason.
Ultimately, this means the X-pipe is the option that makes the most sense if you’re at the top of the power band.
High-pitched, raspy exhaust sound
Slightly more power at top of power band
Freest flowing mid-pipe style
“True Dual Exhaust”
A very rare setup is a “true dual exhaust” or “divorced duals.” While most mid-pipes intersect to equalize exhaust gases, a true dual setup runs straight to the tailpipe with no intersection. Both pipes have their own respective mufflers and tailpipes.
It might seem like this would be the best and freest flowing exhaust form. But X-pipes and H-pipes both benefit from a slight Venturi effect which helps pull exhaust. A true dual exhaust doesn’t produce the Venturi effect.
Many V6 owners have pointed out that this difference in performance is very slight though. Meaning the true reason to get a mid-pipe for them has been modifying their exhaust sound.
Single exhaust option Upgraded Y’s make sense if trying to reduce total mods
Restrictive Fewer options
Great muscle car growl Low-end torque improvement
Not as free-flowing as X-pipe
Freest flowing option Best in high RPM applications
More expensive usually
H-Pipe vs X-Pipe
For most people, the debate about which mid-pipe is right for them comes down to X- vs H-pipes. Both of these mid-pipes provide a way to equalize exhaust gases and create a smooth flow.
X-pipes have a slight advantage for drivers who are mostly concerned with top speed and efficiency at high RPM. H-pipes have a slight advantage for launches thanks to better low-end torque.
But for most people, it comes down to the differences in sound.
Mid-Pipes and Headers
While mid-pipes usually attach to the exhaust manifold, if you’re planning a serious exhaust overhaul you may also be considering headers. If that’s the case, it’s important to make sure your headers and mid-pipe are compatible.
If you’re interested in long-tube headers, then your mid-pipe will almost certainly need to be the same brand. If you want to mix brands, you’ll need to research compatibility a lot more. While there are some good reasons to mix brands, usually it’s best to go with the same one for the best fit.
Different mid-pipes are suitable for different builds. X, H, and Y-pipes all have their own pros and cons. Here's how each will affect your performance, exhaust note, and budget so you can pick the right mid-pipe for your exhaust.