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There is other reasoning besides cosmetics behind dual exhausts.

Dual exhausts having two mufflers permit higher gas flow while at the same time have lower exhaust sound level.

Symmetry is, obviously, the "cosmetic" component of the design. Humans... and living things in general are symmetrical things where symmetry is a defining component of beauty. It only follows we define our cars similarly.

Also consider the fact that the entire rest of a car is symmetrical. A single exhaust, therefore, stands out as a major "wart" in an otherwise harmonious visual package. There is more than one reason the grapefruit-shooting fart can is ugly besides its sound.
I love having dual exhaust it just looks right.

Yes it may be for aesthetics but it would look off if it only had one tip (at least on the SH)
My foz with dual 4" tips

DSC_0852 by Puzzles Photography, on Flickr


DSC_1057 by Puzzles Photography, on Flickr
 

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In their Spring 2008 Drive magazine, Subaru claims to have introduced dual mufflers to the 2009 Forester to reduce back pressure and noise. Must have found a better muffler for the 2014 versions.
 

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Could it have something to do with the PZEV models?

Also, it definitely looks way cooler. But if it's functionally useless, why wouldn't they at least make it a proper dual exhaust and bump the performance along with the visual?
 

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Could it have something to do with the PZEV models?

Also, it definitely looks way cooler. But if it's functionally useless, why wouldn't they at least make it a proper dual exhaust and bump the performance along with the visual?
Because believe it or not the poor 4 popper needs some back pressure to make any torque. One thing these boxers are good for is better torque than typical inline designs.
Personally i enjoy the dual tips. The rest of my 2012 felt cheap (the doors seemed made of tin cans) but the exaust tips made it more appealing. Now if only they'd figure a way to make a Forester/Impreza that didn't shock the hell out of me EVERY time i get out....oh wait they did.....the 2014's. Maybe they integrated a grounding rod as yet unseen.....
 

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Some years ago I was talking to a Borla engineer while trying to improve the output of a Chevy 350HD. He told me that the 350 didn't flow enough gas through a 2.5 inch exhaust to need a dual exhaust-at least while using one of their mufflers (which flowed the same as a straight pipe).

So if a 5.7 doesn't flow enough for a single (2.5 inch) pipe, I kinda doubt a normally aspirated 2.5 needs 2 pipes. Turbo may be another story.
 

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I think other than maybe very exotic(and expensive) cars,manufacturers don't want the expense of two catalytic converters and don't want to have to design the underchassis room for two cats just to have true dual exhausts.I like the looks of my 2012 dual exhaust outputs but don't have any delusions that it helps powerwise.
I believe when they started putting cats on all cars it was pretty much the end of true dual exhausts.

Also other than with a dual turbo,the exhaust is combined for the turbo so it's hard to imagine any benefit from then splitting it back up for dual exhausts
 

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The Forester's dual exhaust is a fake??? How sad. If an engine has 5 or less cylinders or an I6, it should be single exhaust. A vehicle with a V6 or has 8 or more cylinders, it should be a 'true' dual exhaust with an 'X' pipe. Anything turbo should have 1. But should a manufacturer put a dual exhaust on, it should at least be functional and not a fake. /End rant.
Actually, it depends on what you mean by fake. To me fake suggests that one of them is a non-functional dummy. Both exhausts and tail pipes are functional, just not in the way performance enthusiasts think of dual exhausts. The exhaust headers run to a single exhaust pipe which splits mid-vehicle to separate exhausts and tail pipes. A true dual exhaust would have separate pipes running from the manifolds to separate exhausts at the rear. So, not fake, just not a true performance split-exhaust system. My '14 has two functioning exhausts with tail pipes so technically, it is a dual exhaust system.
 

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I think the dual exhaust setup is to improve the departure angle. Two small mufflers instead of one large one make for better clearance. If so then it's not a fake, it just has a different purpose than what you might assume a dual exhaust to have.

Steve
 

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2.5L Aftermarket Duals

So, are there any aftermarket manufacturers that are making or will eventually make a dual (exit) system for the '14 and '15 non XT's? Seems like they would since the bumper cover is already cut out for it. I feel certain that they'd sell well to us symmetrical loving non-turbo owners.
 

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So If I don't care for the look, I figure I can drop 25 lbs by going to a single muffler and at the same time maybe add so attitude to the sound.
 

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Sometimes I like asymmetry

I realize this is an older thread. I'm not especially fond of symmetry for the sake of it. I'd rather have real metal wheels than fake plastic covers. When it comes to the 2014 Forester XT I'm curious about replacing the dual exhaust with a single exhaust....if there is agreement the duals do nothing for the performance of the car?

Any recommendations? I don't want louder nor drone but I'd rather have a single pipe instead of the posturing of a dual exhaust. Thank you.
 

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I realize this is an older thread. I'm not especially fond of symmetry for the sake of it. I'd rather have real metal wheels than fake plastic covers. When it comes to the 2014 Forester XT I'm curious about replacing the dual exhaust with a single exhaust....if there is agreement the duals do nothing for the performance of the car?

Any recommendations? I don't want louder nor drone but I'd rather have a single pipe instead of the posturing of a dual exhaust. Thank you.
Without all your other words... just say, "I preferred a single exhaust. And I put one on." If you're really happy with how it turned out, share pictures of your work and any tips you might have learned with others. That's always appreciated.

But there is no posturing going on. Assuming you've read the entire thread, you're obviously not the first to question why, when the Past use of dual exhausts meant probably more power and a V8 under the hood, does this little four banger have duals. Looked at in today's world, however, and you find good reasons why there are dual exhaust outlets, and mostly dual mufflers, on modern cars.

Noise regulation is the major reason. Two mufflers are better than one, all things equal, for minimizing power loss. But our noise regulations give us little choice... either a more restrictive exhaust, a much larger muffler, or dual mufflers to quiet the horses. To replicate the exhaust flow AND sound level of your FXT with a single exhaust you would need a much larger muffler. But where's it going to go? They take up too much space as it is... but that sound-reducing bulk is shifted into two equal symmetrical locations that minimize the impact on storage and interior room.

The manufacturers would love to reduce costs and use one muffler. They can't.

The world thinks that's a good thing, even those who couldn't care less about power or sound levels. Why? Because symmetry is fundamental to life as we know it. Without belaboring the obvious, an otherwise perfectly symmetrical vehicle with dual, symmetrical exhausts, simply looks Right.

A single exhaust on a Forester XT would actually be more "posturing" than the duals. Make it as effective as duals and it will really make a statement... because it will be an obvious alteration... like an eye patch or prosthetic on a living creature.

But if you like it and want it go for it. Just don't try to convince everyone else. Your why's are yours, no explanation needed.
 

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Knickers in a twist

Goodness! I guess I stepped on some toes. I did read the entire thread, and there seems to be debate whether dual is for anything other than looks or does it infact enhance performance. As the set up is cat back, I don't think my musings are out of line. Yes, the natural world order is symmetry. However asymmetry has a certain flair. It can be viewed as unbalanced or incomplete. But do we all need to agree? This site and others is filled with vanity projects of every shape and size. "How do you like my....?" fill in the blank. There are mountains of people showing their rigs for compliments or who are indecisive about their mods and want to know if others "like" or is it cool enough.

If symmetry is the concern I can always place the exhaust dead center. And.....I never said a thing about "posturing" We're all entitled to like what we like and shouldn't be brow-beaten for it.
 

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Did you read and understand the previous post? If you like to single exhaust then go ahead and post pictures so we can all watch the process. Enjoy the Love.

Laughing at oneself and with others is good for the Soul
 

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Oh my, jump on. So.....a dual exhaust doesn't lend much to performance? Particularly if it is a cat back exhaust? Doubling the mufflers on a single manifold is necessary to keep things quiet? I don't want to change anything if in fact it is utilitarian? If it's for show then I'm not sure why people are getting sore. A'm I being attacked for my aesthetics?
 

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@8lackie in my opinion, a "true" dual exhaust with ELH - equal length headers will add to the engine performance.
A true dual exhaust has dual runs all the way back to the engine. :wink:

As to non-true dual exhaust. It's an appearance thing & I'm going to guess the additional muffler will do a pretty good job of reducing the exhaust sound level. :confused:

More poop here: Single Exhaust VS. Dual Exhaust

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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Oh my, jump on. So.....a dual exhaust doesn't lend much to performance? Particularly if it is a cat back exhaust? Doubling the mufflers on a single manifold is necessary to keep things quiet? I don't want to change anything if in fact it is utilitarian? If it's for show then I'm not sure why people are getting sore. A'm I being attacked for my aesthetics?
Not in a Forester, no. But in other, more powerful cars? Yes, mostly, but not always. I hope that helped.

Oh yea, having said that, I like the dual exhaust.
 
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