My quest for quiet, free flowing mufflers

[Shawn]

My long body 24" dual Magnaflow mufflers is no longer cutting it for being quiet. Now granted they were on my big block Chevy and maybe have 1000 miles on them. That being said, they are WAY too loud on this SBC with dual 3" exhaust. Its possible I already blew out the packing material but the low miles has be doubting that.

I always liked the straight through design of the Magnaflow, Borla, Ultra flo, and a few others. I have also used a Varex remote muffler but those are pricey and not the best for performance when closed. The straight through design sounds great on other cars with a cat but on mine with no cats and a built engine with an aggressive cam its just too much. Rasp is REALLY bad. I researched till 2 am the other night and watched countless of videos. I almost went with the Flowmaster 70 muffler but even that might be too loud after hearing it on 3" straight pipes with a built motor. If I had some room for some 3" resonators I'd install those too but the passenger side is scarce for room with the rotated t-case and shaft there.

I'm now looking at this Dynomax Super Turbo muffler with the longer 20" body. It doesn't seem to hurt the flow too much and the sound is better IMO.

This video shows how good that muffler performs with a modified engine and how good they sound.

Some good talk about this muffler here:
https://www.chevelles.com/forums/13-performance/391504-550-hp-w-dynomax-super-turbos-anyone.html

Any other ideas on quiet yet free flowing muffler for 550hp? Does anyone run the Super Turbo?

 

[AJs72K5]

I dunno. I noticed the 5x8 magnaflows were a bit quieter than the 4x9 magnaflows on mine. Presumably more packing between the internal pipe and the case. But I’m in the same boat. Was almost considering the flowmaster 50 series.

 

[Wes Harden]

I have dual flowmaster 50 series on a sbc 355 6" rod motor, stockish manifolds, cross over, tail pipes to bumper. not 3" thou 2.5" in a Chevelle. nice and quiet in the car those behind well... they know something is not to be messed with

That said I have a single knock off stainless series 80 3" tail pipe behind left rear tire. Sbc 355 stock manifolds. Noise level low I can hear it, if I concentrate on the exhaust over the tires and other rattles, course stereo must be turned down when I do so..... not much

 

[dyeager535]

I'm on a phone with slow service so I'm going to be lazy and not look up what HP dual 3" should support. Something tells me that is more than enough for 550hp.

Which would make me consider mufflers that may not be as free flowing, as velocity is likely already lost. Without some sort of empirical back to back testing anyway, not sure how anyone would know the difference. Exhaust alone is a science.

Anyway, I too am done with loud exhaust. Truck is already loud enough and my hearing bad enough, that I dont need exhaust to add anything more than needed.

When I was researching and looking for the quietest mufflers out there (in stainless) I couldnt find anything to beat the Walker Quietflow SS. I think it was Borla that came closest in terms of sound reduction, but with the Walkers being essentially OEM replacement, and knowing how the OEM mufflers sound, I figured it would be hard to go wrong.

I would like to run a resonator and cat, as my experience with at least the cat is that it does change the exhaust tone, and obviously resonators are supposed to help.

 

[Bent77]

I’ve run the super turbos on some snotty small blocks. Wouldn’t say they are quiet, but less noise than a Thrush welded by just a tick

 

[shady]

The Jones "quiet tone" mufflers sound pretty good and are real quiet at normal driving. They are the same internal design you showed above.

I've ran em on a single exhaust on a Silverado, and dual with H pipe behind a 4.6 Ford. Both sounded good. Town car was actually more quiet than I wanted.

My K30 CC has dual 3" flowmaster super 50s dumping under the bed, right behind the cab. Going down the highway with windows down you can still talk normally. Getting on it is loud though.

 

[Shawn]

I dunno. I noticed the 5x8 magnaflows were a bit quieter than the 4x9 magnaflows on mine. Presumably more packing between the internal pipe and the case. But I’m in the same boat. Was almost considering the flowmaster 50 series.

I have the 24" body (28" long) Magnaflow. Lots more muffler it has to go through. I called Magnaflow and they told me the longer the muffler, the quieter its going to be. I don't think you will like the 50 Flowmaster for a mellow tone. I'm just done with this rasp and drone. I do think the cammed / built engines are much louder than the stock-mild engines.

I have dual flowmaster 50 series on a sbc 355 6" rod motor, stockish manifolds, cross over, tail pipes to bumper. not 3" thou 2.5" in a Chevelle. nice and quiet in the car those behind well... they know something is not to be messed with

That said I have a single knock off stainless series 80 3" tail pipe behind left rear tire. Sbc 355 stock manifolds. Noise level low I can hear it, if I concentrate on the exhaust over the tires and other rattles, course stereo must be turned down when I do so..... not much

The stockish manifolds and H pipe will quiet it down. With having headers and dual 3" exhaust, it really amplifies the noise. I don't think the 50 series or even the 70 series will be quiet enough for me. I didn't know they made and 80 series. If so I will look into it.

I'm on a phone with slow service so I'm going to be lazy and not look up what HP dual 3" should support. Something tells me that is more than enough for 550hp.

Which would make me consider mufflers that may not be as free flowing, as velocity is likely already lost. Without some sort of empirical back to back testing anyway, not sure how anyone would know the difference. Exhaust alone is a science.

Anyway, I too am done with loud exhaust. Truck is already loud enough and my hearing bad enough, that I dont need exhaust to add anything more than needed.

When I was researching and looking for the quietest mufflers out there (in stainless) I couldnt find anything to beat the Walker Quietflow SS. I think it was Borla that came closest in terms of sound reduction, but with the Walkers being essentially OEM replacement, and knowing how the OEM mufflers sound, I figured it would be hard to go wrong.

I would like to run a resonator and cat, as my experience with at least the cat is that it does change the exhaust tone, and obviously resonators are supposed to help.

I'm willing to lose flow or velocity for noise suppression I gave up on a stainless muffler since there is less options out there. The other thing it needs to be is center inlet, offset outlet to match my current stainless exhaust pipes with v-bands. If I could fit 3" resonators, I would go that route but the rotated t-case makes it really tight for space on the passenger side. I've considered cats too but again tight on space in that area plus the heat there. I looked for the Walker Quietflow but they don't have the center/offset I need in the 3" size. Borla XS 3" actually drops down to 2.5" on the inside.

More videos of the Super Turbo. I realize we are not drag racing but gives you good idea what they sound like at WOT under load.

 

[Shawn]

I’ve run the super turbos on some snotty small blocks. Wouldn’t say they are quiet, but less noise than a Thrush welded by just a tick

I realize they won't be like factory quiet but I just hate the upper RPM rasp on straight through exhausts with this engine.

The Jones "quiet tone" mufflers sound pretty good and are real quiet at normal driving. They are the same internal design you showed above.

I've ran em on a single exhaust on a Silverado, and dual with H pipe behind a 4.6 Ford. Both sounded good. Town car was actually more quiet than I wanted.

My K30 CC has dual 3" flowmaster super 50s dumping under the bed, right behind the cab. Going down the highway with windows down you can still talk normally. Getting in it is loud though.

Thanks I will look into those Jones quiet tones. I think the flowmasters are off my list after hearing some videos of dual 3" . Not sure if I can fit the H pipe.

 

[Bent77]

The Nova is probably the closest sounding to the 2.5” ones I’ve run. My pickup had them, but also a cross over

 

[shady]

This is the single I did on the Silverado. It's idling through the vid till I have my buddy hit it a couple times

 

[Bent77]

Also, the step down size inside the case on the super turbo 2.5” looked to be 2.25”

I’m thinking that 67 camaro has 3”
Plus a little motor...

 

[ChrisPerry]

If you like the sound of your exhaust now, try installing exhaust cones. They slip in at the collector end. Don't change sound, just make it quieter.

 

[skunked]

Add a resonator before the muffler.

 

[dyeager535]

Yeah, I was thinking the late K5 mufflers were what you need, but they are backwards for your use...center inlet offset outlet.

Edit: must have been my dyslexia. The later gas engine K5 mufflers are correct for your application.

 

[Shawn]

This is the single I did on the Silverado. It's idling through the vid till I have my buddy hit it a couple times

Thanks! I notice some mufflers can sound pretty tame on a stock-mild engine but it really changes thing with the dual 3" and taller lope cammed engine. Single will probably be quieter than the dual. Now I'm kind of wishing I did 4" single exhaust. Any idea how those are made on the inside?

Also, the step down size inside the case on the super turbo 2.5” looked to be 2.25”

I’m thinking that 67 camaro has 3”
Plus a little motor...

Nope, on the larger body mufflers they don't step down. I was told by Dynomax that the taller bodies do not step down. So the larger mufflers will be a true 3" all the way through. The smaller body mufflers drop down to 2.5". Thats one I did not like about Borla.

If you like the sound of your exhaust now, try installing exhaust cones. They slip in at the collector end. Don't change sound, just make it quieter.

Sounds like that would choke or limit the exhaust but worth looking into.

Add a resonator before the muffler.

If only I had more room on the passenger side.

Yeah, I was thinking the late K5 mufflers were what you need, but they are backwards for your use...center inlet offset outlet.

Actually... thats what I need. 3" Center in, 3" offset out. I thought when I looked last time, there was no option for that unless I was mistaken or they can be reversed. Will have to look again.

Another video that shows how quiet the Super Turbo mufflers are. First ones he puts on the engine.

 

[shady]

The internal pic I found of the quiet tones looked just like the one you posted. Typical continuous tube turbo style

 

[ChrisPerry]

The exhaust cones have more flow than the pipe they go in. Don't choke performance at all.

 

[AJs72K5]

I need an offset in / center out. Although, the Dynomax mufflers are big enough that I'd have to redo the tail pipe for sure.

I get what the internals look like on the offset/offset Dynomax with the two 180* turns, but I'm curious how they run the internals on a center/offset.


EDIT: found a pic of a gutted one.... not exactly what I expected.

 

[Shawn]

I need an offset in / center out. Although, the Dynomax mufflers are big enough that I'd have to redo the tail pipe for sure.

I get what the internals look like on the offset/offset Dynomax with the two 180* turns, but I'm curious how they run the internals on a center/offset.


EDIT: found a pic of a gutted one.... not exactly what I expected.

Crap! You're right. That is not good for flow. Offset/Offset would be the best but I can't do that unless I want to modify the exhaust system.

 

[shady]

You have a small block and dual 3". The center in/out isn't gonna hurt flow enough to matter.