When it comes to picking the right muffler for your vehicle, it pays to do your research. The type of muffler you choose will have a dramatic impact on the overall performance and sound of your ride. If you’re looking to enhance both without compromising quality or reliability, Flowmaster should be at the top of your list. And among their many muffler configurations, the dual in, dual out design really stands out.
After hearing so much hype about these dual in, dual out mufflers, I decided it was high time to try them out on my own truck. I’ve done plenty of mods in the past – cold air intakes, tuners, exhaust kits – but swapping the muffler made one of the biggest differences I’ve ever felt when it came to raw horsepower gains. The sound of the engine was meaner, yet not obnoxiously loud. And the performance increased noticeably across the entire rpm range. Suffice to say, I’m sold on the merits of the Flowmaster dual in, dual out!
The Many Benefits of Dual In, Dual Out Flowmasters
So why exactly does this style of muffler stand out from your typical single in, single out design? There are a few key reasons:
- Increased airflow – By using two inlet and two outlet pipes, these mufflers allow more exhaust gases to flow through. This reduces backpressure compared to stock mufflers, resulting in more horsepower and torque.
- Tunable sound – With two outlet pipes, Flowmaster dual ins and outs allow you to customize the volume and tone of the exhaust note. Close off one outlet for a deeper tone, or open both for maximum volume.
- Highly durable – The dual in, dual out configuration means the muffler has increased surface area. This allows it to dissipate heat more effectively, increasing the muffler’s lifespan.
- Emissions compliant – Many Flowmaster dual ins and outs are CARB approved. This 50-state legal muffler can liven up your exhaust without failing emissions.
- No drone – While loud when you want them to be, many dual in, dual out Flowmasters have chambers and internals that prevent highway drone. You get roar when accelerating, without annoying cabin resonance.
So in summary, the Flowmaster dual in, dual out gives you the best of both worlds – increased power and aggressive sound when you want it, without compromising everyday drivability.
Picking the Right Dual In, Dual Out Model
Flowmaster makes a range of mufflers with the dual in, dual out design. Which you choose comes down to the level of sound and performance you’re after. Here are some of their most popular options:
- Flowmaster Super 40 – The Super 40 delivers a deep, rumbling tone that really wakes up V8 and high-performance engines. It’s one of the loudest dual ins and outs, but has a mellow highway tone.
- Flowmaster 50 Series – With a slightly milder sound, the 50 Series improves flow and power without being over the top. It has a refined muscle car rumble suited to classic and modern V8s alike.
- Flowmaster Super 44 – The Super 44 produces Flowmaster’s signature aggressive sound – loud when you want it to be, but not obnoxious. Provides up to 5-10 horsepower gains on modified engines.
- Flowmaster American Thunder – This dual in, dual out was designed for a rich, throaty rumble that works with larger displacement V8s or trucks. Provides plenty of flow for bolt-on mods or heavy loads.
- Flowmaster Outlaw – As the name suggests, this is one of Flowmaster’s loudest mufflers. It’s a full straight-through design for maximum flow on high HP applications like drag cars or off-road rigs.
So if you want a deep muscle car burble, the Super 40 or 50 Series are great choices. For a louder exhaust on a modified vehicle, step up to the Super 44 or Outlaw. And if you need maximum flow for towing or hauling, check out the American Thunder.
The Powerful Sound and Performance of My Flowmaster Super 40s
For my Chevy Silverado, I decided to go with a pair of Flowmaster Super 40 mufflers. With a few bolt-on mods like an intake, tuner and headers, I wanted a bit more oomph from the 6.0L Vortec V8. But I didn’t want the exhaust to be ridiculously loud either.
After the shop finished installing the Super 40s, I couldn’t wait to fire up the engine and hear how they sounded. Let me tell you – I wasn’t disappointed! The rumble on startup was music to my ears, and settled into a mellow muscle car burble at idle. Romping on the throttle resulted in a deep, authoritative bellow coming from the dual chrome exhaust tips.
Driving around town and out on the highway, the tone was perfectly aggressive without being overbearing. Just a satisfying, quintessential American V8 rumble that put a grin on my face every time I stabbed the gas. Cabin drone was practically nonexistent, even cruising at 75mph.
Not only did the Flowmaster dual in, dual out mufflers deliver on their legendary sound, but the performance improvements were noticeable too. The 6.0L felt noticeably torquier down low, with improved throttle response. It really came alive in the midrange, pulling harder through 4500-5500rpm where I do most of my highway passing. And it loved to rev higher than before, with the aggressive exhaust note seeming to egg the engine on as the tach needle swung past 5500rpm.
For me, the Flowmaster Super 40s were the perfect blend of sound and power. They gave my Silverado the mean muscle car demeanor I was after, without going overboard. The quality and durability of these mufflers also give me confidence they’ll stand the test of time and abuse without cracking or rusting out.
Dual In, Dual Out Flowmasters Deliver On Their Promises
Now that I’ve experienced the transformation a set of Flowmaster dual in, dual out mufflers can have on a vehicle, I’m a believer in their benefits. Here’s a quick recap of how these mufflers delivered for my truck:
- Easy to install – I had a muffler shop handle it, but they said it was a simple bolt-in job on my Silverado. Took just a couple hours.
- Big power gains – My 6.0L V8 feels faster and torquier throughout the rpm band, especially in the midrange where the exhaust opens up.
- Perfect sound – I got the muscle car rumble I wanted from the Super 40s without any obnoxious drone. They strike a great balance.
- Quality construction – The Flowmaster mufflers feature thick gauge aluminized steel and MIG welded inlets/outlets. They should last for years and years.
- Great value – For around $170 each, the Super 40 mufflers gave my truck a whole new performance personality at a reasonable price.
So if you’re looking to liven up your ride, I can’t recommend going with the Flowmaster dual in, dual out setup enough. They simply outperform single in, single out mufflers while delivering that iconic American V8 rumble. You’ll never go back to stock exhaust again after installing a set, I guarantee it!
The Process to Install Dual In, Dual Out Flowmasters
As I mentioned, I had my local muffler shop handle the install on my Silverado. But if you’re fairly handy and have access to some tools, installing Flowmaster dual in, dual out mufflers yourself is definitely doable. Here are the basic steps involved:
- Lift up the vehicle safely using jack stands or a professional lift. Never rely on just a jack when working under a truck.
- Remove the stock muffler and tailpipes by loosening the clamps at the mid pipe and cutting the hangers. A reciprocating saw makes quick work of this.
- Clean the cut edges with a file or grinder to remove any loose rust and sharp burrs.
- Install the new Flowmaster mufflers using the provided or original clamps. Bolting on custom tailpipes is also an option.
- Secure the hangers on the mufflers to the rubber isolators along the frame or body. This prevents vibration and rattling.
- Tweak the position of the chrome exhaust tips so they sit centered in the rear valence. Even small adjustments make a visual difference.
- Start up the engine and check for leaks. Tighten up clamps as needed. Also confirm exhaust tips are aligned.
- Take it for a test drive and listen to that sweet Flowmaster rumble! Enjoy the improved performance and sound.
As you can see, the process is very straightforward when equipped with some basic tools and DIY know-how. And you’ll save on labor costs doing it yourself. Just be sure to take precautions when working under a vehicle.
My Review of Flowmaster Dual Ins and Outs
Now that I’ve lived with the Flowmaster Super 40 mufflers on my truck for a while, here’s a quick pros and cons rundown of my experience:
Pros:
- Noticeable horsepower and torque gains
- Classic American V8 rumble sound
- Aggressive tone when accelerating, not loud at cruise
- Quality construction and materials
- CARB compliant on many models
- Easy to install yourself
- Great bang for the buck performance upgrade
Cons:
- Sound may be too loud for some drivers
- Won’t work with some import 4 or 6-cyl applications
- Professional install recommended to customize fitment
- Louder interior resonance with cab removed or open top Jeeps
- Not as deep a tone as some other mufflers on high revving engines
All in all, for many truck, muscle car, and classic V8 owners, a Flowmaster dual in, dual out muffler is one of the best bang-for-your-buck upgrades out there. The power and sound gains are downright addicting! Just make sure you choose the right Flowmaster model based on your specific vehicle, horsepower goals and sound preferences.
Answering Common Questions on Dual In, Dual Out Flowmasters
I’ll wrap up this review on Flowmaster dual in, dual out mufflers by answering some common questions I’ve seen come up in forums and discussion boards on these popular exhaust upgrades:
Do I need a tune with Flowmasters? Not necessarily, unless the muffler install is part of a larger intake/header/cam package. Flowmasters alone won’t impact air/fuel enough to require a tune.
What about check engine lights? Flowmaster dual ins and outs are CARB compliant, so CELs from O2 sensor readings are unlikely. Clear codes after install just in case.
Will they work with an H-pipe/X-pipe? Absolutely, Flowmaster mufflers pair great with H-pipe or X-pipe mid sections. This maintains performance while tuning the sound.
How is the drone on the highway? Most Flowmaster dual ins and outs use internal chambers to cancel drone. It’s only really noticeable with open top vehicles.
What’s the lifespan? Properly installed, Flowmaster mufflers typically last over 100,000 miles. Their durable construction handles abuse. Look out for rust with road salt exposure.
Can I DIY the install? You definitely can, but having a shop install them makes fitment and alignment easier. Pick based on your skill level.
Do they affect gas mileage? Mildly improves MPG in some cases by reducing backpressure. But the gains are small, usually 1-2 MPG at most.
So in summary, Flowmaster’s dual in, dual out mufflers are some of the best in the business when you factor in sound, power gains, quality and value. And they’re proven to stand the test of time mile after grueling mile. I’d highly recommend Flowmaster for anyone looking to really wake up their exhaust. You’ll be grinning from ear to ear!
