We are talking about a 302/347 in my 65 Mustang. I have a 2.5" exhaust going to 2.25" out the tailpipes with 3 chamber Flowmasters. I haven't really noticed any problem with top end acceleration but I don't have a point of reference.

My problem is twofold. I don't want to sacrifice power but I'd like a tolerable noise level. Now the car is reasonably quiet at idle and not bad at about 2000rpm but sounds like a flat out race car at WOT. I've had people come over the house saying "What the hell is in there!" It's loud enough that I need to be careful where I stomp on it because I'm sure all the cops in the city can hear it.

I am thinking of getting rid of the Flowmasters. I have heard some stuff about other mufflers making more power while being quieter at the same time. I am also wondering if my exhaust is choking the motor. I have heard the the DynoMax Super Turbos are relatively quiet but produce good power. They also have the Ultraflows. I think Hooker has the Aerochambers. Basically there are a lot out there.

So my questions are, do I need a 3" exhaust with my combo? It would need to have turndowns. Or can I get all the power out with a 2.5" with tundowns? What about a reasonably quiet muffler that doesn't impede power? I am assumming that I am better off with turndowns rather than having tailpipes.

My combo is a stroked 302/347 with TFS high port ported aluminum heads(2.05/1.60), 10.5:1 Comp, .543/.571 lift cam, 5spd. Thanks for the help.

If you don't want the car to be too loud, tailpipes are probably going to be on your shopping list. Everybodys limit is different. Some think 3" exhaust with race mufflers is no problem. Some don't want to hear anything. I've got 3" exhaust with Edelbrock race mufflers (which are fairly quiet for race units) and turndowns. At cruise, they aren't that loud at all, but at idle, they will thump on your head.

You could install 2.5" exhaust along with the mufflers you want and have turndowns tacked into place... If you like it that way, fine. If you don't, then go ahead and install 2.5" mandrel bent tailpipes. 2.5" manderel bent tailpipes won't really choke the engine much (if any) more than the 2.5" exhaust by itself. But for the ultimate in "free breathing", it's hard to beat the 3"... especially with a deep breathing 347.

With your engine, I'd definitely get rid of the 2 1/4" tailpipes. You'd probably be happy with 2.5" mandrel bent tailpipes available through Flowmaster or MAC. They make the noise come out behind the car, and are a bit easier on the head.

Aerochambers are supposed to drone like hell. Personally, I like the Edelbrocks. I ported mine at the transition from the core to the end pipes.

Good Luck!

Thanks, that is about the way I was thinking. I figured that the 2.25" were probably okay for my 289 but not for the 347". Actually the local Muff shop is great. They love cars and race cars. They take special care to make good exhausts for fast cars. The quality of the exhaust in the car now is great.

I have heard that the Edelbrocks are even quieter than the Super Turbos. I am not really looking for quiet, to tell you the truth I love the sound now but I just think with a car putting out a lot of power and this sound it's just a matter of time before I wind up in a lot of trouble. I figure a little less noise would lower the odds.

Also I have heard that the chambered mufflers like the Flows don't flow as well as the stright through designs. I'm always game for easy horsepower.

My biggest problem is that I really like the looks of the tailpipes. I might just have to order the pipes you mentioned and just run 2.5" all the way to the back. I think though I'll first run it with new mufflers and turndowns and see if I can get used to the sound and looks.

I should have mentioned in the first post that I also have full length headers.

Alex,

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Originally posted by kcode:
Jaazzy,
Flowmaster offers 2.5 mandrel bent tailpipes for 65-66 Mustangs. Trying to squeeze 2.5 over the axle is a bitch, but they have done is with smooth bends and sectioned pipe.

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Been there, done that...

Several years ago when the mustang was my only car, I had 2.5" exhaust w/flowmasters and muffler shop tailpipes. The guy who did the exhaust was a top quality kind of guy, but had a REALLY hard time with the 2.5" tailpipes. (This was before the mandrel bent units were offered by Flowmaster and MAC) He actually bent FIVE tailpipes before getting two he was happy with... but these were still crimped really bad. There's no substitute for mandrel bends, and no regular muffler shop I know of has one of those machines. (I had standard length mufflers too) That first bend was a b*tch.

Use a short muffler, and BUY THE MANDREL BENT UNITS when installing tailpipes on any mustang.

Good Luck!

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Originally posted by JAAZZY:
Actually the local Muff shop is great.

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I can imagine!

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'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC

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Originally posted by SteveLaRiviere:
I can imagine!

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'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC

I think the hardest thing about exhaust is that in these older vehicles each one of us has a slightly different combination and so it hard for a cut and dry answer. With the newer cars you can be fairly certain that the car will sound the same as the ones tested.

My car sounds great at idle. Not too loud, just mean. At 2000 rpm it drones a bit but I can live with it. At WOT it could wake the dead. It is loud enough to scare the crap out of people I drive by and will set off alarms everywhere I go. I think you are right though about the age factor, I've had the same exhaust now for about 12 years and though it might be a little deeper now with the new motor it probably isn't much louder, I'm just older. We need a bumper sticker for Muscle Cars, "If the Exhaust Is Too Loud, You're Too Old."

From reading a lot of posts I think I've concluded that the quietest performance muffler with still good flow is the DynoMax Super Turbo. I worry though that it will also increase backpressure. I think the Ultraflow is more along the lines of what I want but then the sound reduction isn't as much. From what I gather the Ultraflow is louder than the Flows at idle but quieter at WOT without the mid-range drone. The Turbo is quieter everywhere. The problem offcourse is that it is too expensive to experiment.

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Originally posted by Mpcoluv:
I have a pair of the 2 1/2" mandrel bent flowmaster tailpipes. $100 from summit.
The pipes had to be tweeked a little to fit

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Do NOT use long mufflers on an early mustang. They just don't give much room for that first bend up and over the axle. Regular length mufflers can be a problem too. Regular, universal Flowmaster 2-chamber mufflers were what I had installed on the mustang at one time. (these were the ones the muffler guy made FIVE tailpipes for trying to get two good ones) These mufflers were just too long for a good first tailpipe bend. Shorter mufflers make life MUCH easier when it comes time to fit tailpipes. The 2-chamber mufflers that are part of the late model mustang package are shorter, and fit better.

Shop around and compare specs. My 3" Edelbrock center in/out race mufflers are very small, and fit really well. They aren't too offensively loud either... Either that, or I'm just not old enough.

Tailpipes make a car much more bearable noisewise. The sound comes out behind the car instead of right under it. When the sound comes out right under it, the whole car vibrates. It's kind of hard on the head at idle... But, I can live with it since it's just my "toy", and not an everyday car. Your tolerance may vary.

Good Luck!

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Originally posted by Mpcoluv:
Is the Dynomax welded race magnum with the large oval case the same muffler internally as the expensive stainless steel Ultraflow?
I am considering putting a pair of 2 1/2" Dynomax bullet race mufflers in front of my flowmasters.
Do you think this will add much restriction?

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They're pretty much the same thing. You can pick either of them up and look straight through one side, and see through the other... But you'd be surprised at how much they do indeed muffle the noise. The packing does a pretty good job of absorbing sound.

Those "economy" bullet mufflers from Dynomax (the $39 ones) that are not welded together don't have much packing, and don't muffle very much. These are the ones that are barely larger than the exhaust pipe. The welded ones are still a really good buy (two of my Chevelle buddies have them) and do a good job.

Good Luck!

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Originally posted by Mpcoluv:
...a friend (Vizard) has tested many mufflers on the dyno...the farther away from the collector the muffler is, the more back pressure you see...a pressure wave reflection coming back from the muffler once it is 24" or more from the collector.

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Mpcoluv:
Do you recall if your friend have a crossover pipe between the header collectors and the mufflers during his dyno tests?
I've read that having a 2 1/4" or 2 1/2" crossover pipe in that location WILL ALWAYS reduce the back pressure as well as the noise level from a given exhaust system.....

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Originally posted by Ryan Wilke:
Mpcoluv:
Do you recall if your friend have a crossover pipe between the header collectors and the mufflers during his dyno tests?
I've read that having a 2 1/4" or 2 1/2" crossover pipe in that location WILL ALWAYS reduce the back pressure as well as the noise level from a given exhaust system.....

Are you using a crossover pipe in YOUR car's system?

Ryan

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Yes I am using a 2 1/2" crossover. David used crossovers (h-pipe) on his test.
He said the X-pipe is hard to predict weather or not it will do much over the H-pipe. Maybe that's why about half the Winston Cup cars use the X and half do not....

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Originally posted by n2oMike:

Those "economy" bullet mufflers from Dynomax (the $39 ones) that are not welded together don't have much packing, and don't muffle very much. These are the ones that are barely larger than the exhaust pipe. The welded ones are still a really good buy (two of my Chevelle buddies have them) and do a good job.

Good Luck!

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So the Bullet type (glass pack looking) mufflers do not supress the sound much? Damn, I was thinking of using them as a low restriction resonator before my 3-chambers...

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Originally posted by Mpcoluv:
So the Bullet type (glass pack looking) mufflers do not supress the sound much? Damn, I was thinking of using them as a low restriction resonator before my 3-chambers...

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Well, they ARE realatively cheap... and they can't hurt. Of course the round welded ones aren't -that- much larger, and will work even better. Those "bullet" mufflers I heard were the 3", 3.5", and 4". They were barely larger than the exhaust pipe, and the engines they were behind were fairly radical. I haven't heard a set of the smaller ones. As resonators, they couldn't hurt. Just don't expect the car to be fully "Midasized".

Good Luck!

They might work pretty well as a resonator, but would probably be a bit loud all by themselves.

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Originally posted by chips67:
i do run 2 chamber flows .....vizard says they suck, mike says they suck

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Originally posted by Mpcoluv:
Vizard doesn't say "suck" exactly, just that there are other (cheaper) mufflers that are better. I personally love the sound of my flowmasters, it just the volume.....

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