Hey all,

I'm going to be replacing my stock muffler with a 'warmer' sounding one and I'm thinking of trying a Magnaflow.

Only my ignition is modded.

Any thoughts?


Valiant John

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1969 Valiant V100, 225 S6, Auto, 9" drums, MSD6A, Accel 8.8 Wires, MSD coil, MP Electronic dist, Iridium plugs, Electric fan, K&N air, remote K&N oil, Edelbrock classic AIS shocks, New leafs

Aren't Magnaflow's made by Walker. {subsidiary}
I am not sure. My buddy put some on his V6 Dakota. They sounded pretty good. From all appearances, they seemed like they had a decent quality of manufacture.

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1979 W150 Shortbox
225, NP435, 9 1/4, Dana 44

The Good Life.

i love my magnaflow, its throaty but loses its drone at highway speed. Kinda like a "nice" flowmaster without the CONSTANT drone. Thums up!
It goes great with a 2 1/4 pipe too

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63 valiant v200 Wagon 9.5, Schneider cam, E.I. 22 mpg all day

I am switching from the 14" Thrush version of the FlowMaster 40 to the MagnaFlow 2.5" diameter in/out 5 x 8 x 18" body. It is a much better flowing muffler and allot mellower sounding. The 14" version is much louder compared to the 18" body.

The FlowMaster 40 has allot of restriction and resonance from the internal reverse reflections. The front of my FM40 gets so hot it turned a light cream on the outside of the case. It is loud from 62 to 68 mph, then gets much quieter after 68 mph.

The 18" MagnaFlow is much mellower with no resonance. It is a much freer flowing muffler.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Thanks for the info!

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1969 Valiant V100, 225 S6, Auto, 9" drums, MSD6A, Accel 8.8 Wires, MSD coil, MP Electronic dist, Iridium plugs, Electric fan, K&N air, remote K&N oil, Edelbrock classic AIS shocks, New leafs

Ted, what rpm range are you turning at 62 to 68 mph? The reason I ask is I have twin turbo mufflers about 14" long with 2 1/4" pipes and my car will cause one's head to rattle between 2400 to 2650 rpm or about 43 to 53 mph. I was wondering if these sixes all have that harmonic point regardless of build.

On long trips with the top up, I use those little twist-up foam hearing protection ear plugs. Top down, not so bad, but not enjoyable for any length of time. We have a few old "old car guys" that like to chug along at 45 to 50 mph when a group of us go to shows, and it drives me nutz!

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

wjajr,

My wife is not fond of the FM 40/Thrush resonance at high rpm either. Low speeds up to 50 are fine and it actually sounds sweet. I like to cruise at 60 mph on the freeway which is 2500 rpm on the money. 2600 rpm on up the resonance starts and she gets loud but tolerable......which is 62 mph, 68 mph is about 2750 rpm.

I never thought that a Flow Master would have that much restriction or that the waves that are reflected back would cause that much resonance. The front half of the muffler is just torched from the heat. It is the section with the "V" shaped dividers. I am sure glad it is all welded with heavy material. Basically the engine is just loafing up to 2600 rpm with tons of torque. Since we can't go over 60 mph in this state I stay at 2500 rpm however, it is fun to run it up to 90 mph now and then but she does get loud!

My friend who has a SL6 with the Dynomax Turbo sounds worse than my Thrush/FM 40.
The 18" x 5" x 8" body MagnaFlow is just allot quieter, freer flowing and no resonance. Nice!
The 14" version of the MagnaFlow is much louder, more like a glass pack.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

i built a 2.5" system for my duster, i used a dynomax super turbo and a glass pack in the rear as a resonator. it is quiet and flows like a straight pipes. i ran it with the super turbo alone to see if id like it and it was loud. i get no resonance inside, really get almost no noise inside.

jamesdart,

I tried that combo with the Thrush/FM40 and it made the resonance in the Thrush go crazy loud. It was unbareable between 62 and 68 mph. Very quiet before and after those speeds.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Running Smithy's on mine and I love it!

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If it was easy, everybody would be doing it.

i get zero resonance. if i drive with the windows up i cant hear the exhaust at all. i wont ever run flowmasters on anything again. they are built to last. they sound good on other peoples cars, just not mine. they with drive you crazy on a long ride.

Thanks Ted for the tip.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

i work at a muffler shop and before that, i thought that all flowmasters were loud and obnoxious. that was until i was educated on how flowmasters work and how they are supposed to built. the FM is a "scavenger" muffler, so if the exhaust is built right, the muffler will actually start to pull the exhaust out of the engine resulting in better economy and power. the secret to making a FM work is to put a tailpipe that is at least 18" long and to use one size smaller pipe for the tailpipe. for example, if you have a 2.5" pipe from the header/manifold, run a 2.25" tailpipe to the bumper. the resonation and the drone will not happen. the reason the smaller tailpipe works is Physics. as the exhaust gas gets further from the engine, it cools and contracts. in order to maintain gas velocity through the system, you have to go to a smaller pipe, which also helps keep the exhaust flowing through the pipe and not tumbling out.

i put a FM 50 on my wife's Subaru Impreza and was amazed by the difference in how the engine ran and how the car drove. it is no louder than stock, picked up 1-2 mpg, and made a big improvement in bottom end. what i did was to upgrade the pipe from the cat to 2.25" and put a 2" tailpipe on it. the exhaust does not resonate and there is no drone whatsoever. all this is what i have learned from my boss who was educated and trained by FM in the 80's.

if you don't want to spend the money on a FM, a Walker Dynomax SuperTurbo is an excellent alternative and has a similar sound. however, the system should be the same way, as the same principles apply. the exception is that you won't get the scavenging effect of the FM.

zedpapa

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1970 dodge dart w/225 /6 bored .040" over, holley 390cfm w/vac. sec., compcams 252s, clifford shorty headers w/2.5" exhaust w/flowmaster, f-body 11" front discs, aluminum A-833OD, 8 1/4 w/3.21 SG
soon to have 5 gears!!!

zedpapa: Warning; possible thread kidnapping taking place here, but I guts to know.

This is interesting to me. I realize that vibration, resonance, acoustics, and wave engineering is extremely complicated requiring math skills way beyond my three semesters of calculus & differential equations covered just forty short years ago. All of which is now located in a bad sector of my brain, or in a urinal some where in North America...

After crawling under the heap with a measuring stick, I should clear up some afore mentioned misinformation on exhaust size and muffler brand.

My car has Shorty Clifford Headers, twin two inch pipe back, entering at an off set, to 13" x 9" x 4" Sonic Turbo mufflers located just before rear axel & exiting center from the mufflers, with two inch pipe, to the bump'ah ending at 340 stile chrome rectangular tips. As previously mentioned, there is an annoyingly loud resonance in the 2500 to 2700 rpm range with this exhaust system.

I don't know if a Sonic Turbo muffler is of the scavenger stile, or just a crappy, cheep tin-can, one clamps on to say there is a muffler back there.

My question zedpapa: do you think a smaller diameter tail pipe would kill this racket, or do I need to up grade to a longer muffler as well as reduce tail pipe diameter.

Also, presently I have no "X" pipe in this system, when standing out back, that engine sounds nasty at idle from the non balanced pulses coming from each bank. Would such a device also help to increase power & torque from a slant six engine enough to justify the added expense?

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

if it was my car, i would go back to single exhaust. duals really rob a lot of bottom end power especially from a smaller engine like the slant. think duals when you have a really healthy big block. the setup that i would recommend would be to buy or build a nice y-pipe with a 2.5" collector and run 2.5" to the muffler and run a 2.25" tailpipe to the bumper. use a 50-series FM which has a resonation chamber in it to help with undesirable side effects. one trick we use is to get one with 2.25" inlet/outlet and open up the inlet to 2.5" to minimize restriction to the muffler. if the system is working right you get a burn stripe at the back end of the delta plates where all the exhaust comes back together.

we build exhaust systems for RVs and work trucks as well and they always get a single exhaust because you get more torque with it.

FM, as far as i know, are the only scavenger-type muffler that i know of. over the last 30 years my boss has tried everything under the sun and keeps coming back to the FM and the Walker line of mufflers. they are also one of the few mufflers that last. no packing to blow out of baffles to rust out.

zedpapa

P.S. the 40 series is a race muffler. that's it. nothing more.

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1970 dodge dart w/225 /6 bored .040" over, holley 390cfm w/vac. sec., compcams 252s, clifford shorty headers w/2.5" exhaust w/flowmaster, f-body 11" front discs, aluminum A-833OD, 8 1/4 w/3.21 SG
soon to have 5 gears!!!