Tech: Modding The Mustang Exhaust System

So you have this Mustang and it’s great. It performs extremely well, looks sexy, drives like a dream and is engrained in American iconography like a Greek column. There is something missing, though. Something that harkens back to the Mustang’s early days, where you could hear the monstrous rumble of a huge carbureted V8 for miles before that muscle car actually came into view. The sound. Our friends at Stage 3 Motorsports provide a huge variety of exhaust components for 1996 to 2012 Mustangs that recaptures all of the huge, booming sound that the Mustang lost somewhere along the way and lets all five of your senses feel the power of your car.

They can help you bring back the brutal sound that screamed of raw power born in a simpler time where lax emissions standards probably took a good decade off everyone’s life, but let the Mustang and other works of American-made muscle car art really sing. Modern Mustangs, sadly, have had some of their teeth pulled in regards to their exhaust notes through emissions controls that keep your car from turning the planet into a deserted, post-apocalyptic wasteland and by Ford attempting to cater to the most Draconian of HOA noise ordinances. We are here to help you fight back.

The best place to start if your goal is pure sound with minimal, if any, actual performance enhancements is the rear of the Mustang. If you happen to own an S197 from the 2005 model years on up, you’re in the advantageous position of only needing an axle-back exhaust kit to get a decent muscle car growl. Axle-back kits replace the stock chambered mufflers and exhaust tips with a complete system that usually includes performance mufflers and tips, but can also completely delete the mufflers for even more aggressive sounds.

Axle-backs are extremely easy to install and are generally several hundred dollars less expensive than comparable cat-back systems, that aren’t required for actual sound gains, because of the updated design of the S197. Owners of 1996 through 2004 Mustangs are not as fortunate. Ford used a mid-muffler setup for the exhaust systems on SN-95s that put the mufflers BEFORE the kickover pipes and require a complete cat-back exhaust in order to get any kind of sound. In general, a cat-back kit replaces most, if not all of the exhaust components from the factory catalytic converters all the way back to the tips with high performance, aftermarket gear. The slight bit of good news is that a cat-back generally provides slight performance gains by using mandrel-bent piping instead of the factory’s back pressure-inducing crimping. Even though cat-back exhausts are available for the S197s, their performance characteristics are generally not worth their increased price and similar sounds can be achieved by just using axle-back kits.

Moving toward the front of the car, we have the mid-pipe. The sheer variety of aftermarket mid-pipes is a tad overwhelming, but they all serve the same purpose: replace the restrictive factory h-pipe with a more efficient design that’s meant for real power gains. Everything from that point on gets complicated, but we’ll try to break down some of the basics without causing aneurysms or nervous breakdowns. There are two basic mid-pipe designs, the x-pipe and h-pipe. Each are shaped like their respective letters of the alphabet and x-pipes generally will improve performance the most, while h-pipes create more sound with approximately the same tones as first and second generation Mustangs. Both x-pipes and h-pipes can be catted or off-road, meaning they either come with aftermarket catalytic converters or completely delete the converters for massive power gains at the expense of not being street legal in some areas.


Even catted x-pipes are not legal for street use in California or other states that have adopted CARB-like regulations. For keeping your Mustang 50-state legal, we have a few different clamp-on pipes that weld in just aft of your factory catalytic converters while still giving improved exhaust performance and sound. Mid-pipes are also available in two size configurations on top of all their other options: long mid-pipes, like this catted x-pipe from Pypes, are designed to fit the stock exhaust manifold or shorty headers; short mid-pipes, like this Pypes off-road x-pipe, are specifically built for use with long tube headers. Though some mid-pipe and long tube headers can be swapped and intermixed, the folks at Stage 3 strongly recommend using headers and shorty mid-pipes made by the same brand to avoid confusion and possible fitment issues during installation.

We’re finally out from underneath the car and into the engine compartment which leaves us with yet ANOTHER choice between shorty and long tube headers. Long tube headers derive their name from their elongated design that features tubing that stretches all the way to the underside of the Mustang and deliver huge performance gains, with some long tube systems generating up to 40 extra horsepower. The two major drawbacks to long tubes are their high cost (some are upwards of $1000) and that they are not legal for street use in some areas due to emissions regulations.

Shorty headers, on the other hand, are 50-state street legal and far less expensive than their larger cousins. These headers simply replace the stock exhaust manifold with more efficient tubing that leads into your stock or stock-length aftermarket mid-pipes. That being said, horsepower gains are considerably lower with the best shorties showing maybe a 15 horsepower gain on a good day with the stars aligned just right. The shorty versus long tube argument is basically one of compromise between raw power, cost and legality.

Ford’s Mustang was born and bred to roar, and despite some of the current rules and regulations that have popped up over the years, there’s still plenty of room to customize, improve and optimize your Mustang’s exhaust system into something with a unique sound and unmatched performance on either the track or street. Stage 3 Motorsports can provide you with every exhaust component that you need, whether you’re trying to make your Mustang sound like an old school muscle car or turn it into an 11 second dragster or road racing monstrosity. The amount of options is a lot to look at all at once, but breaking down each exhaust component into your personal need, application and local emissions regulations will allow to arrive at the perfect setup for your car. Emission standards and environmental regulations are constantly changing, but there will always be a way or two give your Mustang a classic sound while still obeying the EPA and CARB. Just keep in mind that your neighbors may appreciate you less.

Article written by Jason Locke and courtesy of Stage3Motorsports.com

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