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How to find the right muffler?


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Old mufflers and the entire exhaust past the headers were rusted and leaking and so were replaced.  Guy at the shop asked what sound profile I wanted and I said I'm a cruiser, not a racer, so I'd like a nice, low rumble at the stop light.

I did get a nice rumble at the stop light.  But I also got 90db at 50mph and that's unbearable.  '73 Convertible 351C 4V with a C6 and 3.25 rear end gears that runs at about 2600rpm at 50mph.  At 90db you can not even have a conversation.

Advice?

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Sorry to hear - or not hear- your problem. I've been down that road numerous times over the years.  Seems hard to find the perfect match for both at idle and then while you are driving.  Most of the manufacturers such as Flowtech , Magnaflow and Flowmaster have sound recordings along with info on each of the mufflers they carry.  Borla is another good one to check out also.  This might give you a better idea of what you are looking for.   I run 3" straight back and ended putting a 4" round  Flowmaster in front of my Magnaflows to help  quite them down a little.    Good luck on finding that perfect sound.  

Edited by Kilgon

Kilgon

 

 

"The only dumb question is the one not asked"

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20 minutes ago, Sheriff41 said:

I've been a big fan of these for a long time.  https://www.dynomax.com/mufflers/super-turbo-mufflers  I have headers on my '72 and these produce a nice mellow tone and loud enough for me when I mash the loud pedal.  May be a little quieter with manifolds vs. headers.

+1 on the Dynomax Super Turbos, I've used them on several different vehicles.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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Well, I'll throw my 2 cents worth in here. Back when I got my 71 Mach 1, 351C 4V, it had Flowmaster 40's on it. Nice sound but, blew your ear out at around 2k-2500 rpm. The drone was ridiculous. A couple of summers back, I replaced them with  2 1/2"Flowmaster FX. These are similar to the Dynomax I believe, straight through, but with glass packing. They are a lot quieter driving around the neighborhood, but when I stand on it, yeah well, heads turn. The drone is far less, but there is some that I really don't mind too much. Here's a short video of my car with the Flowmaster FX mufflers. I think this is the right one. Search under Stanglover and Flowmaster FX mufflers.

https://7173mustangs.com/forums/topic/37896-mustang-walk-around-2/?do=findComment&comment=385872

 

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Geoff.

 I learn something new every day!

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Just put on flowFX mufflers as well. Very little drone with a reasonably mellow tone and I was able to eliminate the drone entirely by adding a pair of resonators. 

Still have a great tone when you get on it, but the sound level when you're cruising is very tolerable.

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Plain Jane | 1971 F Code Coupe 302/C4 Automatic

Goin' to Town Rig | 1971 F100 Ranger XLT LWB 390FE/C6 Automatic

Commuter | 2018 Tesla Model 3 Midrange RWD

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I have Dynomax Super Turbos and they sounds good, but ironically I find them a little too tame. So Im planning on making the switch to the FlowFX mufflers over the winter. 

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16 hours ago, Stanglover said:

Well, I'll throw my 2 cents worth in here. Back when I got my 71 Mach 1, 351C 4V, it had Flowmaster 40's on it. Nice sound but, blew your ear out at around 2k-2500 rpm. The drone was ridiculous. A couple of summers back, I replaced them with  2 1/2"Flowmaster FX. These are similar to the Dynomax I believe, straight through, but with glass packing. They are a lot quieter driving around the neighborhood, but when I stand on it, yeah well, heads turn. The drone is far less, but there is some that I really don't mind too much. Here's a short video of my car with the Flowmaster FX mufflers. I think this is the right one. Search under Stanglover and Flowmaster FX mufflers.

https://7173mustangs.com/forums/topic/37896-mustang-walk-around-2/?do=findComment&comment=385872

 

Two things:  First, I forgot to mention the "drone"!  Besides being just too loud at highway speed, the tone/pitch is right at that super annoying point.  Second, your video perfectly hits the nice idling low thrum I'd like.  I'll have to take your word on "at speed".

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Dynomax Super Turbos are my go-to "cruiser" muffler. You definitely need a quieter muffler on a convertible. 

The standard offset inlet/center outlet 14" shell or case length is what most places use. The 20" shell model is a bit quieter, used them on my '72 T-bird and 71 XR-7. They're a tight fit on a 71-73 Mustang, but are doable if your exhaust guy is willing. 

 

2133270491_dynomaxsuperturbo.thumb.JPG.d4d50f7a3c0544a06bafb6f39389ccae.JPG

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I had Magnaflows for a number of years but like anything they seemed to lose their mellow tone. Last winter I went with some Hush Thrush turbo mufflers and like the tone. Pretty quiet until you hit the loud pedal. 

[align=left]Jeff T.

 

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passengers. [/align]

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I have the super turbos and I love em! Loud enough when I jump on it but very nice for cruising. I can hear my radio easily when just going down the road. I’ve been running these for about 7 years now. I added headers a few years ago which of course made them louder, but still not to loud. I will get theses again if need be, but they still look in great shape.

John - 72 Q Code

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50 minutes ago, jpaz said:

I have the super turbos and I love em! Loud enough when I jump on it but very nice for cruising. I can hear my radio easily when just going down the road. I’ve been running these for about 7 years now. I added headers a few years ago which of course made them louder, but still not to loud. I will get theses again if need be, but they still look in great shape.

John, good point about headers. I forgot to mention my car has manifolds, not headers.

Geoff.

 I learn something new every day!

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On 10/26/2021 at 10:27 PM, MKSpeedlab said:

I have Dynomax Super Turbos and they sounds good, but ironically I find them a little too tame. So Im planning on making the switch to the FlowFX mufflers over the winter. 

My solution was to use the Dynomax STs with exhaust cutouts. This setup gives you the flexibility of running relatively quite with cutouts close but then you can control the "volume" by opening the cutouts as much as you want. Find the version of cutouts where you can control the opening manually rather than either fully opened of fully closed. I am typically cruising with the cutouts closed, but when going to a car show or in the track I open them slightly to get the rumble sound and reduce any performance restriction the mufflers and pipes provide. I don't typically run them fully open because it gets obnoxiously loud but then my EFI struggles in ide due to the location of the O2 sensor near the cutouts.

Edit: to clarify, what I mean with opening/closing the cutout flap "manually" is really via an electric motor, but you can control the motor from inside the car by manually hitting the rocker switch so you control the amount of flap rotation you desire instead of fully open or fully close.

Edited by tony-muscle

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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2 hours ago, midlife said:

How to find the right muffler: get behind the car, and look underneath.  It will be on the side opposite the left muffler.

Bwahahahaha!

So, who's a funny boy Eh!

Geoff.

 I learn something new every day!

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2 hours ago, midlife said:

How to find the right muffler: get behind the car, and look underneath.  It will be on the side opposite the left muffler.

Bwahahahaha!

Easy for you youngsters to say, makes my knees hurt too much :classic_tongue:

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“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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23 hours ago, tony-muscle said:

My solution was to use the Dynomax STs with exhaust cutouts. This setup gives you the flexibility of running relatively quite with cutouts close but then you can control the "volume" by opening the cutouts as much as you want. Find the version of cutouts where you can control the opening manually rather than either fully opened of fully closed. I am typically cruising with the cutouts closed, but when going to a car show or in the track I open them slightly to get the rumble sound and reduce any performance restriction the mufflers and pipes provide. I don't typically run them fully open because it gets obnoxiously loud but then my EFI struggles in ide due to the location of the O2 sensor near the cutouts.

Edit: to clarify, what I mean with opening/closing the cutout flap "manually" is really via an electric motor, but you can control the motor from inside the car by manually hitting the rocker switch so you control the amount of flap rotation you desire instead of fully open or fully close.

I dont suppose you have a pic under the car that shows where you put the cut outs? Im planning on making the exhaust myself and right now Im just trying to lay it all out on paper since the engine is out. 

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This is one before welding it all together but it shows the location right after the header collectors. I since installed "half" turndowns to push the exhaust downwards.

20160815_094044.thumb.jpg.2694dbfb1cadb493ec826c16f8817fc8.jpg

Edited by tony-muscle
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20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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On 10/28/2021 at 6:16 AM, Tnfastbk said:

If you run an X pipe or an H pipe that will also make a difference. When I switched to the X pipe my car got considerably quieter.

This.

You'll get an awful cackle out the pipes otherwise.

RC92234, what mufflers are on it now (the new ones)? A crossover might be all you need.

Pete - MotoArts Decals and Signs

'71 Sportsroof 351C-4V/4-speed - FINALLY under construction - no, wait, on hold again...

'90 Mustang 7-Up 5.0 ragtop, rolling beater - SOLD

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