Advice on Muffler Replacement

[77 K20]

I have 3" Thrush chambered mufflers. Run over rear axle and out the sides. Very deep mellow sound.

I ran those on my 400. Sounded awesome. They are kinda a flowmaster copy- but a lot cheaper in cost. However when I swapped out the 400 to the 383 they had such an annoying drone/resonance around 2,300 RPM that I got rid of them. Swapped to a Magnaflow muffler. They are more quiet than I thought they would be. However when you romp on it they get loud.

 

[Rusty Nail]

I had a buddy named Corvette Mike that bought a pair of Dynomax Race Bullets and I HATE THEM.

 

[Craig 85]

I don't like straight through mufflers except for 30-36" glasspacks. I went with Flowmaster Super 40's as they have a larger case that give a deeper tone than standard 40's.

Here's my smogged up 454 at idle. Pipes exit under the hitch.

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[curse]

Porters

 

[Charlie]

I've had 2 Flowmaster 40's on mine for a year and ready for something else. Tired of the "drone" (roar) from them. Not sure if I want to get Flowmaster 50's or maybe MagnaFlow.

 

[Catbox]

I've had 2 Flowmaster 40's on mine for a year and ready for something else. Tired of the "drone" (roar) from them. Not sure if I want to get Flowmaster 50's or maybe MagnaFlow.

You can add (I know, it sounds weird) high flow cats under the truck and it will mellow the sound quite a bit.

My 454 truck has a set of Flowmaster 40's under it and it is quite docile until you really get on it.
At this point it is too quiet for me.
I have to run the cats as I live in a smog state where anything '75 and newer has to pass a visual and the sniffer.

I found the trucks set on craigslist for the price of one muffler.
You can see junior putting them under the truck semi temporarily.

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[Catbox]

When I redo my whole exhaust system here this summer.
I will be putting long tube headers to a full 3 inch dual exhaust.
Since I have the cats that take the raspberries out of the exhaust, I will be using these Jones Flowpack single chamber mufflers under it.

They should allow for more grumbly noise from under the truck.

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[Rusty Nail]

I've had 2 Flowmaster 40's on mine for a year and ready for something else. Tired of the "drone" (roar) from them. Not sure if I want to get Flowmaster 50's or maybe MagnaFlow.

This is why gawd made crossovers. It would be interesting to simply add an h pipe and observe the difference both in sound AND useable power/driveability.

Because it will MURDER the drone and then youd be able to hear it. Think how much money youd save. Im talkin about spendin 40 bucks yo.
Plus it wont pop. I imagine you will then enjoy the tones, rather than wondering what all the fuss is about.

In the name of science, naturally.

 

[ahoppj]

Talked to the muffler guy down the road and I think I’m going to go with the super 44 flow masters

 

[bucket]

When I redo my whole exhaust system here this summer.
I will be putting long tube headers to a full 3 inch dual exhaust.
Since I have the cats that take the raspberries out of the exhaust, I will be using these Jones Flowpack single chamber mufflers under it.

They should allow for more grumbly noise from under the truck.

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Those are my new favorite cheap mufflers. I've hardly listened to the radio since I installed them on my 454 Suburban.

I still think Hooker Aerochambers sound a bit better and more refined, but the cost is substantially higher than the Jones mufflers.

 

[SquareRoot]

I like Flowmaster 40 series.
Thinking I might put those on my 502.

Straight pipes and head straight to the nearest tunnel.

 

[Bextreme04]

When I redo my whole exhaust system here this summer.
I will be putting long tube headers to a full 3 inch dual exhaust.
Since I have the cats that take the raspberries out of the exhaust, I will be using these Jones Flowpack single chamber mufflers under it.

They should allow for more grumbly noise from under the truck.

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Wait.... they made you put Cats on your 79 3/4 ton? You know it didn't come from the factory with Cats right? The oregon regs say that you don't need one and even has the amount of emissions that should be measured for 79 and newer heavy duty vehicles without Cats and 85 and newer WITH cats. So they aren't even expecting by regulation to see Cats on anything newer that 85 in Oregon.

Or is yours a light duty 3/4? If it has a GVWR over 8500lbs(should be 8600lbs I think for a 79 C20 Camper Special) you shouldn't have t odo anything but make sure it doesn't leak too much and hook it up to the sniffer. My 1980 K25 that was sold in Sheridan originally had no emissions equipment at all. No vapor canister, no cats, no EGR, nothing.

 

[jake wells]

Jones flowpack v baffle mufflers is what i use and like. The quality is good and they are made in the USA.

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[Catbox]

Wait.... they made you put Cats on your 79 3/4 ton? You know it didn't come from the factory with Cats right? The oregon regs say that you don't need one and even has the amount of emissions that should be measured for 79 and newer heavy duty vehicles without Cats and 85 and newer WITH cats. So they aren't even expecting by regulation to see Cats on anything newer that 85 in Oregon.

Or is yours a light duty 3/4? If it has a GVWR over 8500lbs(should be 8600lbs I think for a 79 C20 Camper Special) you shouldn't have t odo anything but make sure it doesn't leak too much and hook it up to the sniffer. My 1980 K25 that was sold in Sheridan originally had no emissions equipment at all. No vapor canister, no cats, no EGR, nothing.

My truck has a GVWR of 8,200 lbs.
It also is a Canadian truck and has a smog system sticker under the hood.
I don't know what all it came with as it has been fiddled with over the years by the previous owners.
There are cats under it now.

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[Bextreme04]

My truck has a GVWR of 8,200 lbs.
It also is a Canadian truck and has a smog system sticker under the hood.
I don't know what all it came with as it has been fiddled with over the years by the previous owners.
There are cats under it now.

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LAME! I went and looked a the heritage brochures and it looks like they upped the GVWR between 79-80. Turns out my K20 was optioned with the heavier duty tires and heavy front spring package, which is why I have the 8600lb GVWR and standard emissions with no extra smog stuff. I was surprised to see the highest GVWR for a C20 in 79 is the 8200lb option. I think you still wouldn't have the emissions stuff if it wasnt sold in canada though. 1978 was when canada had the last major changes in the smog laws and companies got a significant tax break for implementing the new standards, from what I could find.