Picking the best performance exhaust system for your car or truck depends on a few factors—but perhaps the biggest is making sure you’ve got the correct exhaust pipe diameter respective to your engine’s power output.
There’s no one-size-fits-all answer here either, because you have to balance exhaust backpressure with exhaust flow to ensure optimal performance.
You’ll also have to consider exhaust scavenging too, you can learn more about that here: Exhaust Scavenging, Explained
Back in the day, many hotrodders would simply grab the largest diameter exhaust pipes they could find and slap them on. The logic was the larger pipes automatically meant better airflow—but once you dive into the science, you could actually be losing horsepower with pipes that are too large for the specific engine they’re attached to.
Again, you’ll have to consider several factors.
That said, there are some basic guidelines to follow when picking the best exhaust tubing diameter based on the kind of horsepower you expect to make. You can reference the chart below for some general guidance.
General Exhaust Tube Diameter Guidelines
| Power Level | Single Exhaust Diameter (OD) | True Dual Exhaust Tubing Diameter (OD) |
|---|---|---|
| Up to 200 HP | 2.5″ | — |
| Up to 250 HP | 3″ | — |
| Up to 300 HP | 3.5″ | — |
| Up to 425 HP | 4″ | 2.5″ |
| Up to 500 HP | — | 3″ |
| Up to 700 HP | — | 3.5″ |
| Up to 850 HP | — | 4″ |
| Up to 1,000 HP | — | 4.5″ |
Video: Understanding How Back Pressure & Exhaust Tubing Diameter Relate
As alluded to above, a major factor in determining the optimal exhaust tubing diameter for a given application is a little thing called “Exhaust Back Pressure.” And to explain how that all relates, our pals at Summit Racing made this short video.
Thanks to a handy grade-school science experiment, it’ll add some visual clarity to the topic. So if you want some explanation behind the chart listed above, check this out:
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Exhaust systems are far more than just a jumble of pipes under your vehicle. Picking the best exhaust system for your specific application can be a complex, nuanced process. The good news is, if you know what your expectations are, then picking the right aftermarket exhaust becomes really easy.
To help you out, we’ve got oodles (yes, oodles) of articles and tech stories on exhaust systems. If you’re in the market for an exhaust system upgrade, here are some good articles to check out:
- A Beginner’s Guide to Aftermarket Exhaust Systems
- How To Choose an Aftermarket Exhaust System
- An Introduction to Exhaust System Components
- How Does an Exhaust Pipe Affect Engine Performance?
- How Much Horsepower Does a Dual Exhaust Add?
- What is the Purpose of a Crossover Pipe on an Exhaust?
- Exhaust Scavenging, Explained
Expert Exhaust Tech Podcast
If you really want to get into the weeds on modern exhaust tech—and how you can still build excellent power in the modern emissions era—check out this podcast interview with Rich Waitas from MagnaFlow.
We spoke with him on a range of topics, and it’s packed with good insight if you’re piecing together a new performance exhaust system for your car, truck, or SUV.
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