Ford Mustang Muffler Comparison Test - American Rumble
Aftermarket Mufflers Sound Great, But Is One Better Than The Others? We Test The Power And The Fury Of 15 Mufflers
According to Webster's Unabridged Dictionary, a decibel is "a unit used to express the intensity of a sound wave, equal to 20 times the common logarithm of the ratio of the pressure produced by the sound wave to a reference pressure, usually .0002 microbar." Uh, on second thought, just think of it as the horsepower of sound.
After a K&N air filter, an after-cat exhaust system is likely the second modification a Mustang owner adds to his new ride. Let's face it-the factory exhaust system just doesn't do justice to the power that's under the hood. The only way to announce you're a real player on the street is with a set of large-diameter tailpipes and throaty mufflers. But the big decision is which muffler to buy for your Mustang. Well fortunately your friends at 5.0&SF are always looking out for you. And we were a bit curious to see how today's modern mufflers stack up against one another (we have Mustangs too...).
The trick in the magazine world is balancing the time needed for such comprehensive testing, the location of a suitable test car, and the borrowing of a chassis dyno for the time required. Fortunately for us, we long ago developed a trusting friendship with Rick Anderson at Anderson Ford Motorsport in Clinton, lllinois. In addition to running AFM, Rick simply loves to dyno parts. He enjoys finding out what parts work on certain combos so he knows what to sell you when the phone rings. Likewise, it helps him decide what parts to stock, and it occasionally gives him ideas for developing new parts. The bottom line is, we know Rick gives us the straight scoop, and he doesn't even mind giving up some of his free time to give it to us.
After Rick agreed to test a few mufflers for us (we always add to his list, and he always seems to agree without complaint), he had to track down a suitable test 'Stang. He wanted to use a naturally aspirated car to ensure the repeatability of a test certain to be dealing with a handful of horsepower difference. Naively volunteering was AFM cus-tomer Jason Moore, whose '90 coupe kicks out 370 hp to the rear wheels and packs high-11-second potential. It was the perfect car to push our mufflers beyond what your street 'Stang is likely to run. Jason not only allowed us to make 66 dyno pulls with his car to ensure repeatability, but he also stuck around from 9:30 a.m. to 8:00 p.m. to help Rick with the test. Thanks, Jason!
So, what did all this testing uncover? It turns out today's mufflers are all good. If you want to squeeze out every last drop of power, there are a few standouts, so check the captions and dyno sheets for the details. But all the mufflers are so close you really can't go wrong. Just find a pair that sounds good to you and bolt 'em on. Better yet, all the mufflers handily outperformed an open exhaust, so you can tell that annoying guy in the neighborhood with the jacked-up Nova to put on some mufflers and he'll actually be faster.
There's so much data here, we simply don't have room to dissect it all, but you have it now, so you can choose the mufflers you are interested in and run the numbers through Excel if you are really serious about eking out every last horsepower. If so, Rick Anderson says to pay particular attention to the average horsepower between 4,700 and 6,600 rpm. This range is critical for drag racing this combo. Rick says the best muffler in that range is the Bassani Real Street, but it's probably too loud for the street (and that's saying something coming from Rick). The Hooker MAXflow, both Borlas, and the MagnaFlow closely followed the Bassani RS with good average horsepower in that range. In the end, we say find one that sounds good to you and your wallet and go have fun.
Not only did Jason Moore help dyno test his car 66 times, but he also assisted Rick in logging the decibel outputs of each muffler at idle, 2,000 rpm, and wide-open throttle using a handheld dB meter from Radio Shack. Of course, this was done in the AFM dyno room, which likely made them all a bit louder, but all were subject to the same conditions. If you're hunting for the best power from the quietest muffler, it looks as if the Borla XS is your muffler. Most were close at lower rpm, while the loud mufflers stood out at WOT.