that is a helmholtz resonator designed to eliminate drone at a certain frequency. problem becomes where can you put it and are other sizes available. larger pipes tend to be louder. what size you need depends on your projected HP.
did you find this on ebay?

 

I am researching the same thing. Research thrush hush and dynomax turbo. Also walker makes quit mufflers. I am trying to balance sound but not lose performance. I think I settled for the dynomax super turbos for my application.

 

How about installing a 6 banger. I hear they are quieter?? V8’s cause a ruckus.

 

Your desire to quiet the exhaust as much as possible will undoubtedly degrade exhaust flow and eliminate any power increase that the headers would provide.

So I must inquire, what therefore, is the purpose of having exhaust headers since they are doing no good ?

an exhaust system is just that, “a system”, and all the parts have to be designed or “intended” to work in harmony with each other. If the systems parts are not in harmony, but at odds with each other, then the result will be disappointing .

Free flowing headers + quiet and thereby restrictive mufflers are a poor combination

Z

 

Your desire to quiet the exhaust as much as possible will undoubtedly degrade exhaust flow and eliminate any power increase that the headers would provide.

So I must inquire, what therefore, is the purpose of having exhaust headers since they are doing no good ?

an exhaust system is just that, “a system”, and all the parts have to be designed or “intended” to work in harmony with each other. If the systems parts are not in harmony, but at odds with each other, then the result will be disappointing .

Free flowing headers + quiet and thereby restrictive mufflers are a poor combination

Z

Good point, I know my set up seems contradictory but the reason I am going with headers is because I have a new Blueprint engine, and their cylinder heads are different from stock cylinder heads. They list that they partnered with a few manufacturers to match their cylinder heads. It would certainly bother me to have an exhaust manifold that doesn't quite match the engine. Header Recommendations

Thanks everybody for the different suggestions, I'll have to take a look at them and check out some videos. I've also read some good things about Borla ProXS mufflers,anyone have experience with those?

 

I'm a fan of the turbo style mufflers. My go to is the Summit Racing house brand. Well made, won't piss your neighbors off with a nice growl when you get on it. They're inexpensive too.

 

I tried a pair of turbo mufflers mounted under the rear seat with tail pipes out the back it was quieter than the side exhaust but developed a bad drone at 2000 rpm. disconnect the tail pipes and the drone goes away.

 

 

Mustang Steve uses Walker Quietflows behind a 427 with very little negative affect on performance.

My preferred mufflers are Dynomax Superturbo Dynomax Ultra Flo and Thrush Hush. All USA made.

 

 

I was sleepy and I pushed the play button twice.

 

Mufflers, you don't need no stinking mufflers.

 

In regard to the Helmholtz chamber, are they attached in front of, or behind the muffler?

 

That's a great question, actually. It should work either way, but the muffler itself will change the pulse frequency and amplitude. I'm going to guess that the bigger pulse before the muffler works better with the resonator pipe stuck on the collector side.

 

Dynomax Super Turbo will give you a quiet cruise, but have a nice throaty sound when you step on it.

Mustangs use the offset inlet / center outlet configuration. The 14" shell length models fit best, part numbers 17730, 31 or 33 depending on your pipe size. An even quieter Walker muffler would be the QuietFlow.

 

A little late to the party here, but those 21424 are going to be a very tight fit on a Mustang floorpan. The 19" shell or case length is five inches longer than the DynoMax Super Turbos that I suggested on the first page.

 

I had this discussion with my muffler shop and they put on two Cadillac mufflers in the duals. This was behind hipo manifolds and h pipe. Pretty quiet at idle and a nice sound when you get on it. I can't see a part number on them and don't know the year of Cadillac. Something you may consider.

 

Criminy, I can't think of any muffler that would be more restrictive than a Cadillac muffler. But hey, if you're happy, you're happy.

I would also suggest the Dynomax mufflers. I worked on Kelly's Mustang several years ago. It has a 289 with Dynomax mufflers. It sounds healthy without being loud. If you decide the Dynomax mufflers are too loud, then you can add resonators. FWIW, I dyno tested my Mustang with only Magnaflow mufflers and again with resonators added. There was absolutely no difference in the numbers.

 

How about a stock dual exhaust system? I would think that would be the quietest.

 

It still frustrates me that when I had my dual exhaust installed, I got estimates from two very good exhaust shops and both absolutely refused to install Dynomax mufflers. Both said they were junk and would not last. I'm still baffled by this. Both shops said I could buy the mufflers wherever I wanted and they would install them, so it's not they were looking to overbill me for the mufflers. Both recommended Flowmasters or Magnaflow. I really didn't like the sound of the Magnaflows; major drone! This is why I had resonators installed.

 

Yes, it's a crying shame about the short longevity on those Dynomax mufflers. I got mine put on in 2000, and they are unfortunately still perfect, with no holes or problems. I did shoot a couple field mouse nests out of them after leaving my car parked next to a field for a few years after I had the engine fire...

... so, yep. Unreliable for sure. Heh.

 

I have heard that on a dual exhaust car, a potato in one tail pipe makes it quieter.

 

Install Honda Civic factory exhaust system with two mufflers. Then add cutouts at the headers.

 

Are you saying Honda Civics don't come from the factory with a coffee can muffler?

 

Beware of drone with aftermarket system, there are hundreds of posts on how to deal that nuisance, you could go broke trying the suggested cures mentioned.
You want quiet go stock with cast iron GT manifolds. I used the Ford stock “Made in Canada” system available from most places, NPD, Branda etc. in your case I believe Long tube headers are a waste of money as well as causing fitment issues.
I put correct stock resononator/ transverse muffler system my 289 and was happy .When I upgraded to a 331 I used the same exhaust but with a set of tri-y headers I was more than happy.
With the added cubes and CR of the 331, it was noticeably throaty at idle and acceleration but still quiet.

 

In my case i am not concerned with the loud so much as get it out back without drone.
the tail pipes seam to be causing the drone.

 

I was guilty myself until I educated myself. I am going to change out the flow masters on my 331 / long tubes. I didn’t realize they flow much worse than many options that are also more quiet.
I had a SC before and loved that car!! Smooth ride and plenty of go!!

Lotta people will not believe this, they think loud=power.

For years I drove a Thunderbird SC, and I can tell you, driving down a back country road windows open at 100 mph (which the SC could reach in a few seconds) all you could hear was the rustle of the leaves I blew off the road.
[/QUOTE]

 

I’m planning a set of flow master 70 series. Not sure they will fit under a mustang but for sure they will fit under my Galaxie project.

Turbo mufflers sound good but I wouldn’t call them quiet. And I’m looking for a deeper sound. Turbo mufflers are a step in the direction of glass packs as far as sound goes.

Did you look into factory take offs from newer mustangs? They are quiet and flow enough to support over 400 hp. It would require a little fab work to get them hung under a classic.

 

I’m planning a set of flow master 70 series. Not sure they will fit under a mustang but for sure they will fit under my Galaxie project.

Turbo mufflers sound good but I wouldn’t call them quiet. And I’m looking for a deeper sound. Turbo mufflers are a step in the direction of glass packs as far as sound goes.

Did you look into factory take offs from newer mustangs? They are quiet and flow enough to support over 400 hp. It would require a little fab work to get them hung under a classic.

I would like to point out that turbo mufflers, glasspacks, and Flowmasters (chambered mufflers) don't usually change the pitch. That is mostly the size of the exhaust pipes you use. The modulation, tone, and volume level are what the muffler will change - as well as where you put it.

Turbo mufflers are the quietest, flattest sounding out of the three types you mention. No sharp cracks or cackles out back, but not as quiet as an OEM muffler either. My car's exhaust with a 5.0 HO and 2.25" was plenty loud to set off all the car alarms in a Davis CA parking garage, any time I gave it a little gas going up the ramps.

Glasspacks are flat out savage. They blat like a 7th grader learning how to play a trombone, and on decel, they cackle with glee and sometimes help shoot fireballs, clearly happy about the whole thing. They really do sound mean, offering the 'classic muscle' tone, but they are hard on you, out on the highway if they're shorties.

Chambered mufflers are very popular since the 80s. They drone like no other, if you get something like a 40 series. It's just an empty can with a few beveled pieces of metal inside that are supposed to help sound waves bonk into each other a little to cancel some frequencies. But as I have said many times, they sound like flashlight firecrackers in a culvert. Hollow. Empty. Like the soul of anyone that runs them. (Okay, that's maybe not really true - but I do hate them. =) )

If you want a lower pitch, use bigger exhaust pipes, put the mufflers closer to the headers, and make more power so you have bigger exhaust pulses so it will boom. Forsaking the 1-2% horsepower of a crossover will also give you more side-to-side burble, and sound like attitude.

 

'Once installed, you will have a NINJA for a car.

 

If my goal was quiet, the factory muffler setup would be it.

 

Bigger is better when it comes to mufflers. Bigger mufflers will normally dampen more. Just look at the huge transverse muffler used stock on Mustangs. The long case (20" case I think) Dynomax Super Turbo or similar Walker (both brands are from the same company) will fit in front of the rear axle on a Mustang, if you got an tight bend between the muffler and rear axle.
Those long case turbos are basically identical to mufflers found on some factory stock cars. One of the Dynomax ST mufflers are neak named "Hemi muffler" since it copies the stock muffler used by Mopar under Hemi cars.

 

I had an exhaust installed on my "66 convertible with a set of 19" long mufflers over the summer. I only have a few hundred miles on the car but I like the sound. Its mellow at idle with little drone on the highway. I've had Dynomax Super Turbos on it before, and it's quieter now. I run 351w iron manifolds on the car (poor-mans hi-po). with a stock 2.25 351W H-pipe.

Tom

 

Here’s what my Summit mufflers sound like with my foot in it. Leaky header gasket has been fixed