I'd call it "dual flow path" before I'd call it "dual chamber". The pic 18psi posted above is the muffler that I've got on my car, but its an 12579/14579

 

Here's a quick clip of my exhaust, this is the single path one

 

Seems pretty quiet to me, thanks deezums!

 

Doesn't seem very straight through.
Have a top, diagrammatic view?

The spring loaded flapper has been holding up fine.

 

See thread "bro's up on muff" for discussion and such.

 

I don't have any pictures, so I drew this one. It is single chamber 3" perforated stainless the whole way thru, with two pie cuts like pictured.



There are pics in this glorious thread
https://www.miataturbo.net/diy-turbo...op-muff-67263/

 

https://www.miataturbo.net/diy-turbo...op-muff-67263/

EDIT: Bringing the Lol's

 

<p>Yeah I saw that and laughed too. &nbsp;Google's automated copyright **** is getting scary. &nbsp;inb4 skynet</p>

 

https://proxy.zalmos.com/browse.php/...ww/b0/fnorefer

fight the machine!

 

Huge *** 12589 muffler.

Looking inside of it.

 

12578 appears to be straight thru:
MagnaFlow Exhaust Products - For Trucks, Suv's, American Muscle, Diesel, & Sport Compact Vehicles


The only thing that might be described as "dual flow" is their "XL" series, which, isn't straight through:


Or is your muffler one of these single-in/dual-out?:


Your photo suggests it has an expansion chamber, instead of a 'Y' pipe inside.

???

 

18psi should have labeled his photo as a 12579 since that's what it actually is. It's 3" inlet, two straight-through 2.5" centers, and a 3" outlet. Hence "dual flow"

 

Anything less would be uncivilized. I have a 1x579

 

Subbed to this thread, i have this 3" MAG 13219 universal XL performance, center inlet offset outlet
I really wanted a quiet setup so i chose a baffled muffler and used a vibrant resonator that is installed where the cat would be, but the system still drons at 3700 rpm and it gets old on the hwy and now it rattles at 3k pretty bad.
So i am looking for a new muffler now

 

Interesting. However
a) 18psi's muff anus pic above doesn't resemble your 3rd drawing... it looks like there's an expansion chamber. I can see what appears to be the ends of 2 perforated pipes
b) I couldn't find a description of it on Magnaflow's website

???

 

I'm somewhat at a loss here, I'm not sure what else I can do to try to convince you.

In the above drawing pretty much everything inside the rectangular muffler body is made of 3" perf tube, other than the dual one that has twin 2.5" tubes. The thing you keep referring to as an "expansion chamber" is a Y section made of 2 pieces of roughly stamped steel. Its not a perfect Y but it does split the 3" flow into the 2.5" tubes, then recombines them at the other end. At no point does it open into the body of the muffler.

I mean, I actually own that muffler. If I had it here I'd be happy to take more pics for you but its at a friends place up near SF at the moment.

In fact, it looks almost exactly like this thing inside the muffler:

http://www.summitracing.com/parts/mpe-10778

And that's funny, because not only is it also made by Magnaflow, I also own that part as well, its part of the exhaust on my truck

 

you broz should really bro up on muff
cause
it's
all
right hurr

 

Anyone have any idea how much horsepowers are lost with the 12578? My wife and I just took a trip to the Mitty in the Miata, Va. to Ga. We could'nt hear the radio, so we cut it off. The drone gave me a headache after a while. Would lie to fix that without loosing my horsee's.

 

Dag, I meant the 12579.

 

??? indeed, dude. I literally posted a link to Magnaflow's product page for the exact muffler you're talking about.