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Magnaflow Muffler (11h?)

NYCBlueZ71

NYCBlueZ71

Full Member
Joined
Jul 2, 2002
Messages
231
Location
Boca Raton, FL
I'm running this Magnaflow muffler:
offcenter.jpg

Which is Part #12289

My goal was to get maximum sound suppression while retaining good flow and backpressure.

My question is, What muffler are you running and how would it compare to mine? Wouldnt this muffler have better backpressure than a short body muffler?

-Rob
 
NYC,,,

I am running the 5x11 Body Part # 12579 ... It is according to Magnaflow going to have the most sound suppression in all their truck Mufflers ...

See pic below ...

The part # you have there is the 5x8 case size ... Your Case length is 24" and mine is 22" ... I don't know if a straight through muffler like yours of the 5x11 12589 (straight through) would sound much different ... But the 12579 (5x11) has a straight through flow pattern with a twist ... It is a center/center 3" but the insides flow like a diamond shape more or less ... It's called a dual-core... It goes 3" and inside goes dual 2 1/2" then back out 3" ... There is like an "island" in the center that apparently splits the flow albiet still straight through, and this is supposed to enhance sound deadening inside the truck ... So comparing your muffler to the 5x11 straight shot muffler may be similar, but comparing the one you have to the 12579 (dual core) wouldn't be the same... As the 12579 was built to address interior resonance... (again according to magnaflow)

11H
 

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Nice, Thanks for the quick reply (y)


I do notice some resonance, but much less than any muffler ive owned before. I am intrigued by the split intenal pipe reducing resonance, it makes sense.

Maybe i should run another in-inline round body muffler....
 
I have the 12589 and have no problems at all...NO interior resonance, a little more throaty at idle and a low roar at WOT.

I could not be happier with this choice.....a simple muffler swap, kept the stock pipes in place.


Thanks to 11H for the earlier threads and advice...YGMN too!

Bio....Brad

out!

Having modded every vehicle I have owned since I was 15 (20 yrs ago), I am very aware of what resonance is...and YOU DO NOT WANT IT! I have personally installed 4 sets of headers (from Hooker on 82' F150 to B&B/Corsa on my 02' Vette) and have had many full pipe systems installed. I had resonance 2 times, one with a Vortex Muff on wife's 01 Pathfinder...put on a Magnaflow...much better now; and once the vette....SLP's loudmouth.

Resonance. Some get it, some do not. ???
 
NYC,

Check with NW_Nick if you want feedback on this muffler. We took his off to put the 70 series Flowmaster #530722 on because of resonance. Prior to it's removal, we had tried to quiet the resonance by installing a resonator in front of the Magnaflow #12289 without much success.

The #12289 works brilliantly on the 8.1L's when you use two, but on the 5.3L, no.

11h is right to utilize the 5 x 11 Magnaflow, our testing, as well as Magnaflows, show this to be a superior application for the 5.3L AV.

Those claiming the #12289 has no resonance, probably havn't enjoyed a performance muffer without resonance before. Some people it just doesn't bother. Go figure.

Cheers
 
I wont even try to compair to the expance of knowledge that 11h has but, Im a muffler Mech. this is just my experience.
My shop stopped pushing the magnaflow mufflers due to the fact they have broken at the rear pipe before a year was up.. we had to warrenty them because it was less than the 1 year 1200 mile warrenty we give.

Personally I run the Flowmaster 50 series, I don't get much resonance. Now ther are options if you want to futher reduse the resonance. You could install a resonanator before or after the muffler to further reduse the sound and resonance.

Just my two cents,
Ken
 
You are dead on about Magnaflow's "rustout" problem on the (bottom) rear neck where it meets the case Kenny.

Magnaflow has stated, and redesigned the manner in which the necks meet the case as well as changed their welding techniques, however, the rustout/fatigue (plastical deformation) still seems to occur, although at a later date.

I still don't believe that is a reason to condem Magnaflow, it's a good product, and they will warranty the product without argument. The main problem though is the repeated payment to have your warranty product installed. Our shops will not charge warranty labor on products (such as Magnaflow) that seem to have an inherent design flaw, regardless of the date of failure.

Although, some shop owners see this as a major hassle, and either refuse to sell Magnaflow products, or nick the customer for labor on each warranty. You can hardly blame them since they don't produce the products they sell, and they still need to pay their techs.
 
This is off the subject, but I had an Edelbrock RPM series muffler on my 94 Sonoma. It has the same internal split as you are discussing above. Granted, it was on a V6 & not a V8 but I really liked the muffler. It has a lifetime warranty, I had it on the truck for 6 years with no problems. It seemed to flow pretty well and I was happy with it.

MBT
 
Meineke did me a great deal, they were out of Magnaflows but convinced me to get a Cherry bomb Vortex muffler and it sounds sweeeet!! It sounds almost stock until it gets above 1900 rpm. They had to fab a couple of short pipes to reach the Y pipe. I didn't realize how huge the stock muffler was. The size of a medium sized suitcase.
But it wasnt as big as the muffler taken off of a Silverado before me, you could've made a canoe out of that muffler!!
Anyone in Central Fl. go to Meineke muffler in Longwood on US 17/92, they will treat you right!
:B: :love: :love: :B:
 
(y)Zilla dawg, you're dead right about the stock muffler. Keeeeerumba, it's a load.

The weight loss may account for the improved gas milage :2:
 
Av Zilla,

I'm in Orlando and would love to hear your exhaust some time. I'm shopping for a muffler swap w/ stock pipes. Hopefully we will try to organize a get together of some type for Central Florida folks (hear that, guys, I said WE ;)).

If you're not too busy before that eventually happens, give me a shout and maybe we could meet up.

Rich
 
11h, do you know of anyone installing the longer 30" body SS Magnaflow muffler Part # 14592 on a 5.3. It's the 5X11 oval with single in and dual out design. I am looking for something louder than stock, but the wife needs to be happy with it too. I have had flowmasters in the past on a '92 Z71, and it was a bit too loud for the family.....thought I would give Magnaflow a try. Thinking of installing it with some chevy dumps out each side..if possible. I realize the duals out each side is a tight fit. Just looking for feedback / opinions.

Thanks :B:
 
Goldfinger3,

I?m not 11h, but I can tell you unequivocally, no, I have not heard on anybody using this muffler designed for a 6.0, and 8.1 on a 5.3. The basic problem is the fact that the outlets (or inlets, depending on your exhaust configuration) are designed to be used on a dual head pipe system such as the 8.1 and 6.0. That is why the dual inlet/outlet size is 2 ? inches. I know this muffler is reversible, but you don?t want 2 ? inch outlets.

Further, the 5.3 doesn?t have adequate exhaust pressure to make this large core muffler function correctly as on a 6.0 or 8.1. As far as your prior use of Flowmaster on your 1992 Z71, what series was it? Was it a 40, or 50 series? I?m guessing it was since it has only been a recent phenomenon installing the Big Block 70 Series on small block motors because of resonance.

I am also not familiar with the term ?chevy dumps out each side?. If you mean ?kick outs? in front of the rear tires, your wife will hate you no matter what muffler you use. The lack of any length of tailpipe only contributes to the drone, and resonance. Running two tailpipes out behind the rear tires is not a big issue for a competent custom bender. The driver?s side is tight, but infinitely do-able.

Ciao
 
Muffman, that's why I wanted to ask the question. I will probably go with the standard Magnaflow (22" body) most are using and have them exit as far back as possible..don't need to upset the wife because she loves the AV as much as me. Thank you for the feedback.

The Flowmaster I had on the old truck was a 50 series. It was perfect at first and got louder over time as they all do.

Thanks Again, GF3

 
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