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 New Flowmaster FX "Magnaflow-style" straight-through mufflers?

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81X11

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PostSubject: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Mon Aug 06, 2018 12:19 pm

So I'm about to replace both cats on my '96 Roady Wagon with Magnaflow cats I bought on Ebay.  One of my original cats is broken inside and rattling.   They are on order now.  Since I'm doing these, I'm considering upgrading the mufflers next.

I've recently removed the stock resonators, and it's louder now...and I like the sound, but sure-enough, I have some "Flowmaster-drone" at around 50-60mph now.   I'm thinking of replacing those 11-year-old Flowmaster 40's soon, and my exhaust guy is pitching me on the new Flowmaster FX, which is a Magnaflow-style straight-through design, not a traditional chambered Flowmaster like my 40s.   The main attraction here is that these are cheaper than both the Magnaflow or the Dynamax.  

Anyone have any experience/heard these?    I'm told they should be a little quieter than the 40's, but will help with the drone and will still sound moderatly loud.    

https://www.flowmastermufflers.com/flowfx/

I was also considering having them modify my stock pipes by adding a crossover pipe to balance the sound, but not sure of that's worth doing on stock pipes.  Has anyone done this, and where did they add the pipe?

Thanks All!

-Texas Mike
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rauldelp

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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Tue Aug 07, 2018 11:19 am

Never heard these, but I ran Dynomax straight throughs similar to those on the 94, and should help some with the drone. These cars pick up drone like crazy tho. Sounded fantastic, just a little head rattley.

On the 93 (TBI single pipe) I replaced my stock muffler with a glasspack, and no resonator and it droned. Catalytic clogged and no checks around here, so that became a glasspack too. Droned like crazy! Replaced the original resonator with another glasspack. Now the drone is effectively gone, but it's also much quieter outside than I wanted. (Methinks I need side exit pipes behind the front wheels. Can't resonate with the body if it's not near the body for long!)

Sounds good, but to get rid of drone I had to make it quiet. That rear section of the car resonates like crazy even with the dynomat all over the floor of the car.

The crossover might make it better, but I've never tried it on one of the wagons.
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81X11

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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Tue Aug 07, 2018 11:31 am

I guess I'll see. I may try these new FX mufflers. Did some reading on them and like what I read.

We'll see.

-Mike
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dmg4

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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Tue Aug 07, 2018 4:12 pm

On a 1996 Roadmaster and 1996 Caprice, I used 3" pipe from the cats back, Walker muffler of the same OAL as the stock muffler, 2.5" H-pipe connection before the mufflers, and deleted the resonators. No drone whatsoever. Nice low frequency rumble outside when you step on it. Relatively quite inside at cruising.
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RedandBlack

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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Tue Aug 07, 2018 4:28 pm

I think you'd be happy with an X-pipe system, Mike. They are a little quieter than straight back duals.

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dmg4

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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Tue Aug 07, 2018 4:35 pm

If you really want to go first class, you'll need the O-pipe from Kale.  See:  http://kalecoauto.com/index.php?main_page=product_info&products_id=41

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RedandBlack

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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Tue Aug 07, 2018 4:39 pm

Amateur hour.

First class is direct exhaust injection. 100% efficient:



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Fred Kiehl

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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Tue Aug 07, 2018 9:46 pm

I have a pair of Magnaflows on my 454, and it still drones (or is just loud). I dumped them in front of the rear axle. I am considering over the axle and behind the wheel exit pipes. I read somewhere that someone did that, and it cured the drone. He discovered it when the drone stopped on a steel grid bridge.
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Rev Bob



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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Wed Aug 08, 2018 6:09 am

The kalecoauto.com site is simply wonderful. If they don't have what you need, you don't need it.


The DEI system was actually under development by the Nazis (really) for submarines. The gas analysis instruments available at the time were not reliable enough to precisely meter in the pure O2 to prevent the engines from grenadeing, and the system never made it into production.
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sherlock9c1



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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Thu Aug 09, 2018 6:56 pm

It's been my experience that these cars drone whenever the resonators are removed simply because of the pipe length between the mufflers and the exit causes a resonance around 1400-1500rpm. If you look at ANY new vehicle, they all have mufflers or resonators within 18" of the tailpipe exit for this reason. If I had to do it all over again, I'd choose a nice muffler and then leave resonators in place. Any aftermarket muffler can be used as a resonator, just something to break up the standing waves before they reflect off the tailpipe exit.
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dmg4

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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Thu Aug 09, 2018 7:27 pm

Quote :
It's been my experience that these cars drone whenever the resonators are removed simply because of the pipe length between the mufflers and the exit causes a resonance around 1400-1500rpm.

See earlier post: With 3" pipe from the cats back, this has not happened with a resonator delete on either my Roadmaster or my Caprice wagon.
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sherlock9c1



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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Sun Aug 12, 2018 1:34 am

dmg4 wrote:
See earlier post: With 3" pipe from the cats back, this has not happened with a resonator delete on either my Roadmaster or my Caprice wagon.

Yes but can you coherently explain why your setup doesn't have drone? Are you using the stock 1.875" over the axle pipes and tails? I'm not trying pick a fight but there's a reason every single OEM does it the way I described.
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dmg4

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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Sun Aug 12, 2018 5:08 am

Quote :
Can you coherently explain why your setup doesn't have drone?

I didn't mean to sound terse.

How about a tautology rather than a coherent explanation: I don't know why it doesn't drone, but it doesn't.  The pipes are a full 3" and they follow the OEM path up and over the axle and end just short of the rear bumper.  The tips are directed 45 degrees outward at the very end.

Perhaps it's like a weak-winded kid try to get sound from a tuba. The cross-sectional area of the 3" pipe is nearly 3 times that of a 1 7/8 pipe.
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Andebe

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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Sun Aug 12, 2018 9:28 am

Source for those pipes,Dave?
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dmg4

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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Sun Aug 12, 2018 3:53 pm

DERP! I just measured the pipes and they are 2.5", not 3".

No wonder women mistrust me.

So, the increase in cross sectional area is about 1.75X over OEM. However, the OEM pipes are sometimes flattened on top immediately behind the cats; not the case with mine, so mine are full diameter from front to back.

My local Monroe Muffler shop mandrel bent and welded both systems for me. So long as they are matching an OEM system part, you are just charged a bit extra for the upsized stock for the pipes.
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sherlock9c1



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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Mon Aug 13, 2018 2:14 pm

That's pretty impressive that they have a mandrel bender. No accordion marks on the insides of the pipes?
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dmg4

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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Mon Aug 13, 2018 2:23 pm

On the exterior of the pipes there are no accordion marks on the insides of the various bends. I can't see inside the assembled system, but if there is none on the exterior, then I don't see why they would form on the interior of the tube.

There is only one Monroe shop in this area that offers the service, and only one guy in the shop who operates the machine.
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Fred Kiehl

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PostSubject: Re: New Flowmaster FX "Magnaflow-style" straight-through mufflers?   Mon Aug 13, 2018 2:55 pm

The pipes bent on a mandrel have some compression in the area bent, so the size is slightly smaller, even though there are no accordion marks. Hydroformed tubing not only has no accordion marks, the diameter is maintained through the bent parts. Hydroforming requires that the tube is first bent on a mandrel, and then is put in a mold. The tube is sealed, then high pressure water is forced into the tube, and the tube expands to fill the mold. Hydroforming is the premier method of making a high flow system.
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