Outside of the automotive enthusiast world, an exhaust system is often viewed as a mishmash of tubes underneath a car.

But if you’re reading this—you know that’s definitely NOT the case.

And so do the exhaust tech experts from MagnaFlow, and Rich Waitas in particular. That’s because Rich has been in the performance exhaust industry for decades and knows an awful lot about modern exhaust systems and the science behind airflow. So we sat down with him to get some insight into muffler design and how to optimize exhaust system performance.

You can catch the entire interview in the embedded player below or in the OnAllCylinders podcast section, and we transcribed ten of our favorite questions and summarized Rich’s responses here as well.


10 Questions on Muffler & Exhaust Tech


1. What’s a Common Misconception Folks Have About an Exhaust System?

“It’s much more than just pipes under the car. In today’s modern vehicles, we’re adapting to all the computer systems that are there, and being sensitive to what the sensors are reading, and understanding that there are thresholds and limits—it’s not that we just need to make it flow the best.”


2. Has That Evolution Changed How MagnaFlow Develops an Exhaust System?

“The big thing we have to contend with, on pretty much any modern performance car out there, is we have to be very cognizant of the control system that the powertrain control module is working with.

“What used to be, with a carburetor, when you increased exhaust flow, you leaned-out the mixture. So you’d just go in, turn a few screws, change your metering rod, power valve—whatever—and you’re fine.

“Well today, it’s not that easy. Even though it’s a plug-in function, adjusting a tune, it still requires a degree of expertise, knowledge, and the equipment. So when we’re looking to develop something, we can’t take something outside the threshold of the computer to learn to.”


3. Is Performance Possible with Modern Emissions Requirements?

“We’re in an era where removing catalytic converters just isn’t an option. The OEMs have spent a tremendous amount of time to make sure those devices are actually capable of operating with, say, a Demon 170—a 1,000 horsepower car.

“Streel legal cars are producing four-digit numbers through a catalytic converter. So the perception that the converter is part of the problem, is kind of an old mentality.

“But there are ways to continue to tune and calibrate tune so that the vehicle remains legal.”


4. How Does MagnaFlow Develop a Performance Exhaust System?

“We figure out what we can with the vehicle, given how it’s designed, where’s the last cat, where’s the break point—what’s comfortable with the car, because we can vary that quite a bit based upon the type of vehicle.

“For a Mustang, we actually tune the exhaust for the acoustic experience we think a typical Mustang owner wants. That’s not going to be the same for the Ram truck owner, that’s not going to be the same for someone running a Toyota Tacoma in an overlanding situation.

“So it is really about listening to what the consumer wants, in those particular categories. With a different consumer, we have different needs—we always go back to the drawing board to figure out what we need to do as an exhaust company to bring out what that vehicle is.”


5. Can a Muffler Outflow a Straight Pipe?

“That’s probably one of the biggest misconceptions out there. People are so used to seeing a race car that has open headers—that dump right after the collector. And the idea is that ‘high performance’ is noisy and loud, and made with the least amount of parts.

“But as we’ve seen on the flowbench, the straight piece of tubing actually flows less than a perforated tube, straight-through muffler.

“It is counter-intuitive, but counter-intuitive doesn’t make it not true. Folks say they want a straight pipe because that’ll make the most power, but if we’re talking about power generated from flow capacity, that’s not necessarily the case.

“The common thought is that a muffler equals restriction, but in some cases it can even enhance the airflow.”


6. Can You Explain the Role of a Crossover, H- or X-Pipe?

“If you’ve got a V-pattern or opposed cylinder motor, you’ve got cylinder banks on the left and right. And if they don’t interact with each other, we’re not taking advantage of the scavenging effect.

“But there is also a distinct sound element. If you remember the true dual exhausts of the 1950s, there’s a very different sound to them, a rasp or a buzz as the revulsion pulse tries to come back up the tube.

“So if we want to tune-out the sounds, there are certain pipes that are better than others. An H-pipe will help get rid of that, but it doesn’t do so as efficiently as an X-Pipe when it comes to creating a scavenging effect.

“They both serve a similar purpose, to balance pressure from the left and the right. The also they act as a tuning device for scavenging and a tuning device for sound.”


7. Describe How You’re Able to Tune for Sound.

“We’ve had classic car owners who aren’t driving their cars as much because it’s no longer a comfortable experience. And it’s not because the old exhaust was too loud—it was because of the drone.

“So with our xMod series, we came up with a way to let builders play with the sound, in a way that they can create the effect that they want.

“Like a trombone, you can adjust the length yourself, cut it to fit, and tune-in that muffler so you can get that great MagnaFlow sound, and also eliminate that drone that occurs with a straight-through performance exhaust.”


8. Are There Limits to Tuning an Exhaust Sound?

“There are some guidelines that help you get a sound of a certain type, but a big expectation from someone new to the market is that it’s very difficult to make something sound like something else.”

“If I have a four cylinder with a turbocharger, it’s not going to sound like a four cylinder without a turbocharger. There’s just no way to manipulate the airflow characteristics.

“Ultimately, displacement, compression, and those primary functions of how those cylinders are firing, have a distinct sound and there’s nothing you can do to get away from it.

“It’s kind of like asking a tuba to sound like a flute, they’re both wind instruments, but the size of the tubing and the air pressure waves that it creates, based on the size of the tubing, is going to have character.”


9. Talk About the Relationship Between Tubing Diameter & Performance.

“For the longest time, the perception was you needed a dual three inch system for performance.

“People understand now that you can’t just ‘go big’ in tubing size. A large tube will actually flow exhaust gasses less efficiently. I think that message is getting out, and we just have to support it with data—and that’s why we do the flowbench testing.

“People are quite surprised when we say, yes, you can support a 500 horsepower car with a dual 2.5 inch system.”


10. Can a DIY’er Install a Modern Performance Muffler at Home?

“I grew up in an era where muffler shops were just as common as a typical diagnostic shops. That’s not so much the case now, and a lot of that is because it isn’t just welding mild steel anymore—everything that comes from the factory these days is some form of stainless. And stainless isn’t the same to weld on, and there are all these other things to consider too, catalytic converters, sensors—having an understanding of that, means that muffler shop techs have to have a different level of aptitude.

“With that, there are fewer of them out there.

“So with the D-Fit line, we wanted to make sure we could provide a product to the consumer that gave them the desirable effects of an aftermarket muffler, without having to be a professional to understand how to install it—and have it somewhat reversible.


You can hear this interview in its entirety in the OnAllCylinders Podcasts section.

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