High Performance Mufflers Dyno Tests

Do high performance mufflers make horsepower gains or are they marketing pipe dreams? It might seem strange why I am writing about this subject on a nature related blog, but it will become abundantly clear below.

One of my hobbies is tinkering and building automotive engines, transmissions, and other drivetrain to increase performance, and more recently to increase fuel economy. Aftermarket muffler manufactures such as Dynomax, Thrush, Flowmaster, Magnaflow, Cherry Bomb, and others all make a good deal of money selling their performance mufflers. They advertise that their mufflers increase performance quite dramatically from a stock muffler, but never seem to have dyno tests to provide proof. They often only quote muffler flow rates in comparison to a “stock” muffler. The question should then become how much flow is required and how much does more than good enough make? 

Finally, Horsepower TV on Spike TV (episode HP2010-07) did a dyno comparison test of some Cherry Bomb mufflers for sound levels and horsepower. I will ignore the sound level tests they did as they have no real world relationship to being inside an enclosed dyno room. They compared Cherry Bomb’s glass pack, turbo, pro, and high priced Vortex brands to a stock muffler on a test engine running headers and dual exhaust. A common stock style muffler gave 472 horsepower, the glass pack gave 480 horsepower, the turbo style muffler gave 477 horsepower, the short pro muffler gave 476 horsepower, and the Vortex muffler gave 480 horsepower. At the very best, the gains were less than 2% and only 1% for two of the mufflers. This proves that more muffler flow is not needed to make performance gains. Performance gains of 5% are barely noticeable, and certainly not worth it for any other than competitive racing.

What these aftermarket mufflers are good for is increasing, quite dramatically, the sound from the engine. Increasing engine sound has a psychological effect of feeling like the vehicle is faster. Now you know that it isn’t from the above dyno tests. The muffler manufactures are truly selling a pipe dream.

When I was younger, I bought into the hype and used loud mufflers, but it was always irritable to drive around a loud vehicle that could be heard from a few miles away. Now that I am much more sensitive to noise pollution, I use high flow stock style mufflers. I can sneak around the back woods and my tires rolling on the gravel make more sound than my engine.

I am writing this article to emphasize that loud mufflers do not help performance and will only make those that use them a menace on the roadways. Believe me, almost nobody wants to hear loud vehicles, especially while relaxing in a country or forest setting trying to enjoy the wonderful sounds of nature. Loud mufflers are technically illegal, because of the disturbance they cause, and at anytime when an officer wants to stop you, they can on sound alone. Save your ears and everyone else’s by using stock style mufflers. Dynomax sells Walker HushFlow mufflers that run very quiet yet offer improved performance than the worst stock mufflers.


5 thoughts on “High Performance Mufflers Dyno Tests”

  1. I’m looking for a quite performance muffler for my 2007 Chevy Silverado wiith a 5.3 liter flex fuel . I have a dual exhaust system on my truck now and I want to keep the dual exhaust system and don’t want to give up the performance . But I want a quite exhaust system. The size of the muffler on the truck now is 22 inches total lenth with 3 inch inlet and 2.25 inches dual outlet . I would appreciate it if you can help me with the muffler.

  2. Walker Muffler part number 22719 or 22784 looks like it would fit your application. It is their Quiet Flow series that should be quiet and flows well enough, especially with two mufflers on your system. Check out the specifics of the part number on their website: http://www.walkerexhaust.com/products/mufflers.asp The muffler can be ordered through many sources, such as Summit Racing, Advance Auto, or your favorite supplier. Be sure to have a cross-over pipe between the dual exhaust to keep the low frequency sound quieter.

  3. only time they are not legal is if exceeds certain db, I have the cherry bomb pro muffler on my 07 jk which passes inspection, from quiet to loud it goes turbo, elite, vortex, pro, glass pack and extreme.

  4. Ok, but you sound like a Cherry Bomb dealer. The whole idea what I wrote is that loud mufflers make very little difference in actual performance, just an emotional thought of performance because you hear the loud engine more. As one who records quiet nature sounds, I learned that it is very irritating to hear useless loud sounds created by humans destroying the peace.

  5. I live on a busy street. I often wish I had a RPG to ‘fix’ the cars with obnoxious mufflers roaring past at 3am. Some have no mufflers! I’ve heard spray foam is a good temporary fix, but you have to catch them parked.
    I bought an old truck with an obnoxious cherry bomb on, it actually gained power when I put a quiet flow on (3-4 clutch started slipping at full throttle), and people still ask what engine the quiet rumble hints at (4.3).
    I saw enough dyno tests of noisy motorcycle mufflers in my youth to know why their owners like them. They remove a chunk of power from the midrange, it then feels like there is more top end, though usually much the same. Yes, they make the bike seem faster by taking power away!

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