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Discussion Starter #1
I was just at my local exhaust guy for a dual exhaust system on my 2500 454. He told me, a dual exhaust is not possible on my car since the catalytic converter is too far back and too big? I think I'll need to go to some other places. I don't see why it would be impossible to do. I have seen many 3/4 ton suburbans with dual exhaust. Does anybody have any idea how to do it?
Thanks, Andy
 

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Go see someone else.

They will have to ether change the converter so that each pipe, has a converter in it to stay legal. Or if you can get away with it just eliminate it, the converter that is.
 

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Discussion Starter #3
As it turns out, there is a few 454 that have a quite big muffler before the catalytic converter, which makes it apparently really difficult to change anything. 3 exhaust shops all said the same thing. None of them knew why GM did that only with a few trucks. Only the 4th guy wants to exchange the muffler to a flowmaster 40 or 50 series for $120. That keeps the stock appearance and doesn't help mileage, but at least the sound would be a lot better.
 

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Andy I have a 1995 454 with the same system. Muffler then a catalytic converter. It is stock.
That is amazing a 12 year old muffler and cat. When this thing needs to be replaced look out.
I like you need more home work on this topic. A 454 needs dual ex,cams,value job and headers.
When it goes the above will most likely be up grades. Inhale and exhale all in one breath.
 

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Not sure why the muffler sits before the cat, but what I do know is design wise the cat sits as rearward as possible, because of the heat generated by the 454's exhaust. It would ruin the cat.
 

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I dunno guys, the older I get the more I like a quiet exhaust note. The baddest sounding ride I had was a 72 Pantera and that hammered out some sweet tones, but I'm loving it more on someone else's car these days. Call me a grandpa, but I like to hear the radio and be able to talk on my cell phone while tooling down the road.
 

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With the sound proofing going into newer cars, you can still get away with a slightly aggressive sounding exhaust, and still be able hear inside the cabin quite well. But I can definitely see where you're coming from. I would never put glass packs in. I'd be happy with something mellow, but strong sounding.

On a different note, I was just looking at the Summit Racing catalog the other day, and they have some small cats that will flow nicely up to 3 inches and a 480ci engine. Andy if you wanted to go dual, you might consider having a cat on each pipe. They weren't too expensive. I think in the neighborhood of $100.00 ea. I'll see if I can find a link to them.

Here's the summit link for now.
http://www.summitracing.com

What size pipes would you be running if you were to go dual exhaust? 2" ; 2-1/2"; 3"
 

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Discussion Starter #8
What size pipes would you be running if you were to go dual exhaust? 2" ; 2-1/2"; 3"
I think 3". I planned to do the cam and air intake manifold, maybe a holley tbi unit in the spring. Somebody on ebay is modifying throttle bodies to 56mm bore. Supposedly works much better, even with the stock tbi injectors. Maybe that's an alternative to the holley. Manaflow makes a cat for the 454 that you can buy on ebay for around $60 a piece. Just look for "Carsound". I think I'll use headers, 2 cats and 2 flowmaster super 40s. I can't wait to hear my truck when I'm done!
 

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I love the sound of my 78 Silverado. It has headers, no cats (didn't come with them from the factory, so they are not required), dual Flowmasters, 2 1/2 inch front to rear with 3" echo chambers exiting out behind each rear wheel. It has a slight cam, so it has a pretty decent lope. When I installed the headers, I just HAD to start it up before I hooked up the rest of the system. Sounded like a drag car.
 

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I think 3". I planned to do the cam and air intake manifold, maybe a holley tbi unit in the spring. Somebody on ebay is modifying throttle bodies to 56mm bore. Supposedly works much better, even with the stock tbi injectors. Maybe that's an alternative to the holley. Manaflow makes a cat for the 454 that you can buy on ebay for around $60 a piece. Just look for "Carsound". I think I'll use headers, 2 cats and 2 flowmaster super 40s. I can't wait to hear my truck when I'm done!
Did you already put a dual 3" exhaust on? From experience I can tell you that dual 3" pipes might be to much. It'll probably sound great but you'll have a loss of performance. I've got a 97 4X4 Suburban 7.4 ltr with ported & polished heads, larger Manly s/s valves, a Vortec supercharger, water injection, a tweaked ECU, and factory exhaust manifolds into 2 & three quarter inch dual pipes. Prior to putting on the charger, but after putting on the pipes I had a loss of low end tourque. It made the truck a dog when pulling any weight. Larger pipes negatively affect cylinder scaveging when the exhaust valves open. When dealing with exhaust on a gasoline engine bigger is not always better.
 
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