The auto world can be a fairly feline-friendly place, with Hellcats, Cougars, Jaguars, Panthers, Tigers, and more all known for prowling the streets. While a cat-back exhaust is actually a different kind of animal, it’s pretty popular in its own right –- and with good reason. Cat-back exhausts, which upgrade exhaust systems from the catalytic converter on back, can be a quick way to increase the power and efficiency of internal combustion engines.
Plus, no extra engine tuning is needed. It can certainly help, but many gearheads say you can generally just bolt on these performance enhancers and go, since they are installed after the catalytic converter and not monitored by the ECU.
Now, it’s true that cat-back exhausts can occasionally be found on some new cars, such as the 2023 Toyota GR86 Special Edition. However, it’s the aftermarket where they’re especially prevalent. For one thing, they’re relatively inexpensive, with setups from the likes of MagnaFlow and Summit Racing starting under $450. They can be effective as well, with MagnaFlow claiming that their products offer power gains in the average range of 10%. Checking the forums shows a much wider range of increases, so this could be a classic case of YMMV — your mileage may vary.
The cat-back basics — breathing easier for more power
If you’ve ever heard people talking about engine breathing, that’s a pretty accurate description of what goes on under the hood. Without getting too deep into the details — or better yet ignoring them completely — you can say that the first step in an engine making power involves getting air into the cylinders to mix with fuel. The last step is pushing the waste gases out. So, from an abstract point of view, it’s not unlike a person breathing in and out.
The main improvement with a cat-back exhaust system is that it makes it easier for an engine to breathe out, usually with wider diameter pipes that allow more exhaust gas to be expelled with less effort. Some systems also will include increased-airflow mufflers for the same purpose. You can compare it to trying to breathe out through a very narrow straw, then removing the straw.
More advanced cat-back setups can even add an oxygen sensor into the mix. It checks oxygen in the exhaust gas and relays that information to the car’s engine control module, which can then adjust how the engine runs to optimize the combustion process. The bottom line is that because the engine spends less horsepower pushing exhaust gases, it has more horsepower to spin your wheels. That can improve an engine’s efficiency, too.
A few final cat-back comments
Other cat-back concerns include their effect on pre-existing warranties. The FTC explains that a warranty is still valid if you install aftermarket parts, but “if someone installs a defective aftermarket or recycled part, or doesn’t install a part correctly, it could damage a part that the warranty covers. If that happens, the manufacturer or dealer can deny warranty coverage for the damaged part and charge you for repairs. The manufacturer or dealer must prove the aftermarket or recycled part caused the damage before they can deny warranty coverage.” Unsurprisingly, manufacturers still fight about this kind of thing anyway.
Then there’s the improved sound quality of cat-back exhausts. Of course, improved in this case is subjective. The less restrictive exhaust pipes change the acoustics for the noisier, creating a more aggressive engine sound that enthusiasts love. However, as with any music, some people like the volume cranked up, others not so much. This could turn into a full-fledged legal issue if you end up violating your town’s noise regulations. Different states have different rules about this, so it’s a good idea to check first.
With that in mind, some folks may ask if it’s really worth it to make this kind of change to your car. Don’t worry, though, you won’t hear them if you rev your cat-backed engine high enough.