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DC Crew
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Discussion Starter #1
You can't.

The Corsa muffler design, as you know has one inlet, and two outlets. One outlet is blocked, so you essentially only use 2 of the 4 exhaust tips.



Our goal was to cut open the Corsa muffler, gut it, and weld it back together to get more growl and volume.



The first troubling thing we noticed was that the Corsa mufflers are actually just a STRAIGHT PIPE inside the muffler! But there is a one inch hole in the straight pipe in the muffler to that goes to the muffler cavity, and 3 very small at the inlet slots, this small hole and slots are there obviously to reduce resonation.

But, make no mistake, the mufflers ARE NOT MUFFLERS in the normal sense... they just look like mufflers.



If it wasn't for the downward tips, you could put a 2.5" pvc pipe right through that muffler (here you'll see one inch).



So, now we are thinking the sound reduction is coming from the center resonators. Right?

So we fire up the car without the mufflers on... it was a judgement call as to whether it got any louder.... maybe 5%... but we expected LOUD.



So, what the heck is going on? We pulled the system apart, shined a light down the resonators, and they were straight pipe too!!!

The sound/volume reduction just seems to be more from the bends of the exhaust, and the smaller 2.5" pipes compared to the 2.75" pipes from the factory.

Not worth $900 to me!!! You could have had this system custom made 2.75" exhaust for $250!

So....

We gutted the cats.... I will start another thread on that and how that made the exhaust sound AWESOME....

Here are some other misc pictures from the Corsa event.



More threads to come on the exhaust subject!
 

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Well Patrick, I agree and disagree. I think the center resonator has fiberglass ro someother similar substance like the old glasspacks back in the day.

I ran my car with the Corsa center res and no mufflers and it was louder, not deafing but definitely louder.

As for the mufflers themselves, the straight thru part is at WOT which I believe you and me both are at 99% of the time. At cruise or idle, the exhaust gets bypassed to the outer tip by the perforations around the inner pipe(at least that's what Corsa explained.

I do agree that the price tag on this unit is ridiculous.

$350 would be a more reasonable price not only for this, but for any system.
 

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DC Crew
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Discussion Starter #3
Mr Mojo said:
Well Patrick, I agree and disagree. I think the center resonator has fiberglass ro someother similar substance like the old glasspacks back in the day.


Nope, solid metal tube.

I ran my car with the Corsa center res and no mufflers and it was louder, not deafing but definitely louder.
All the guys in the shop... I dunno... 5 of us all shrugged our shoulders and believed, if anything, it was marginal.

As for the mufflers themselves, the straight thru part is at WOT which I believe you and me both are at 99% of the time. At cruise or idle, the exhaust gets bypassed to the outer tip by the perforations around the inner pipe(at least that's what Corsa explained.
Nope. The outter pipe is welded shut, this was verified. It never opens. Additionally, since LT4's run rich, my inside tips (the ones that work) turn jet black. Since I am at WOT far too much, the outside tips should turn dirty... which they never have.

Patrick
 

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Interesting. I did not know that about the centers.

I'll take your word for it on the mufflers, I'm not going to be inspecting them any time soon.
 

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My '84 had aftermarket replacement "family-car" mufflers on the back. Quiet - far too quiet - throaty rumble, but nothing more. So they had to go. I had trouble getting the mufflers off the pipe while it was under the car so I dropped everything behind the cat.

Thought to myself - better see what this sounds like!! Very disappointed. Loud, droned like buggery inside the car because the opening was right under the seat, but definitely not F*&*%N' LOUD!!!!, like I expected.

So once I got the mufflers off the pipes I put that section back on and tried again. Still not very loud, but it cured a lot of the drone inside the cabin. There is no centre resonator, only the cat. So with nothing more than some pipe and a cat it's not too bad. Loud, yes, but a Corvette should be. Legal, possibly not, but nowhere near as loud as I expected it to be.

Most of the "sports" mufflers that are available usually have a straight through perforated pipe, with the muffler body packed with fibreglass. This offers little or no restirction to flow but the fibreglass helps to absorb some of the sound.

So the bit about one section being used for WOT and the other pipe being used on idle, sounds like a fair bit of marketing BS and a little too hi-tech for something that's little more than a few bits of welded pipe.

At the moment I'm undecided about whether to just get my pipes extended out the rear of the car or get new mufflers. Personally I think I could get away with just pipe.
 

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Discussion Starter #8
TM-96CE said:
Want to make your Corsa's louder........get rid of the resonator portion, and replace it with a Magnaflow x-pipe. My Corsa's are nowhere near quiet.
Tell me more.... :thumbsup:
 

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Patrick96LT4 said:
Tell me more.... :thumbsup:

Here's what I did. I purchased a 2.5" Magnaflow X-pipe off Ebay ($65). I then had a muffler shop install the Corsa cat-back, but instead of installing the resonator pipe(s), I had them weld/fabricate the X-pipe in it's place.

My Corsa's scream now. They can be quite deafening when you get on it. The resonance exists in the 3000rpm range, but I can live with it. And I still have my cat's.

If I knew how, I'd make a sound file.
 

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Discussion Starter #10
TM-96CE said:
Here's what I did. I purchased a 2.5" Magnaflow X-pipe off Ebay ($65). I then had a muffler shop install the Corsa cat-back, but instead of installing the resonator pipe(s), I had them weld/fabricate the X-pipe in it's place.

My Corsa's scream now. They can be quite deafening when you get on it. The resonance exists in the 3000rpm range, but I can live with it. And I still have my cat's.

If I knew how, I'd make a sound file.
Since I gutted the cats the exhaust volume for my car only went up a few percent in the inside of the car, no resonance at all. (I sure had it with my muffler eliminators!!!!). But, the car is twice as loud outside the car when i stand on it.

I didn't want "loud" as much as I wanted "evil" and.

Plus I picked up some HP. The corsa resonator DOES have an h-pipe style crossover. I would like to put an x-pipe in there but down want any resonance... I will have to play around with it, but winter is coming and it might be spring...

Thanks for the info!
 
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