Help... I am so confused...

georgethedog

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I just talked with someone from Moroso thinking I may be able to slip in some small muffler after my Roe high flow cat right before my Corsa system to quiet it down. Not something very restrictive, but a little something. I won't say who gave me the idea.

Here is the confusion: The guy at Moroso blames the Corsa system for the loudness that is bothering me and swears the high flow cat WON'T make a difference. He said the cat is not causing the loudness, but the Corsa. Corsa says the opposite. The guy at Moroso said I could put the stock cat back on and it would be just as loud as long as I have the Corsa. While on the other hand he said if I left the high flow cats on and put my stock muffler back on it would kill the sound and the car's performance.

I really do not know who to believe, but my feeling is the guy at Moroso deals with Mustangs too much and lower end products and has no idea what the _____ he is talking about.

By the way, he said Vipers are not that fast anyway. His car could beat me. I replied, "Yes, but would your car have beaten me if you would have left it stock?" At that point he shut his pie hole.

Thoughts, comments are very welcome. Thanks.
 

ViperTony

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Sound is relative and what you may think is loud I may think is too quiet and vice-versa. However, I did notice a difference in volume when I replaced my stock cats with RT Hi Flow cats. Then it got louder when I added a Belanger catback and even louder when I added Belanger headers.

What did the Moroso guy say/advise about adding the spiral flows? I assume since he blamed the cats that adding the spiral flows between the cats and Corsa wouldn't do anything which I find very difficult to believe. Try searching the forums as I recall the spiral flows being discussed many times. Someone should be able to chime in about them and their experience with quieting down the exhaust.
 
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georgethedog

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Sound is relative and what you may think is loud I may think is too quiet and vice-versa. However, I did notice a difference in volume when I replaced my stock cats with RT Hi Flow cats. Then it got louder when I added a Belanger catback and even louder when I added Belanger headers.

What did the Moroso guy say/advise about adding the spiral flows? I assume since he blamed the cats that adding the spiral flows between the cats and Corsa wouldn't do anything which I find very difficult to believe. Try searching the forums as I recall the spiral flows being discussed many times. Someone should be able to chime in about them and their experience with quieting down the exhaust.

He said if I added the spiral flows that the system would be so restrictive (even though I have high-flow cats and Corsa) that I would lose all my power and might even have enough back pressure to blow out my spark plugs. He said it would be more restrictive than the stock system. I think he is nuts and it is his first day on the job. ;)
 

TAXIMAN1

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I purchased a 2001, with the Corsa already on.. The car was LOUD... I then changed to RT high flows, the car got LOUDER. But did not bother me, as I was aiming to reduce sill temps.

On another GTS I owned, the car had a full stock exhaust, and was quiet as a mouse. And to be honest, was a nice change.

If your shooting for quiet. I would find a FULL flex pipe back, stock exhaust and transplant.

Try JonB. I bet he has one from a Donor Car.
 

ViperTony

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He said if I added the spiral flows that the system would be so restrictive (even though I have high-flow cats and Corsa) that I would lose all my power and might even have enough back pressure to blow out my spark plugs. He said it would be more restrictive than the stock system. I think he is nuts and it is his first day on the job. ;)

I'd try installing the stock cats...you can probably get them for free aside from paying for shipping. Find yourself a good muffler shop that can fit/weld/install them for you for a decent price. My buddy did this and it did quiet down the system. The Corsa still sounded great but it wasn't as loud as with the hi flow cats, relatively speaking. :)
 
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georgethedog

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I purchased a 2001, with the Corsa already on.. The car was LOUD... I then changed to RT high flows, the car got LOUDER. But did not bother me, as I was aiming to reduce sill temps.

On another GTS I owned, the car had a full stock exhaust, and was quiet as a mouse. And to be honest, was a nice change.

If your shooting for quiet. I would find a FULL flex pipe back, stock exhaust and transplant.

Try JonB. I bet he has one from a Donor Car.

Interesting... What I really want is something that is somewhere in between the two you described. Maybe that is not possible. :(
 

Tom F&L GoR

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My experience with sprial flows : I put them on my '94 sidepipe car (hoping to make it more quiet) in place of straight through mufflers (perforated straight tubes, insulation around the tube.) The spiral flows were much louder and more drone. I actually wore ear plugs on a 45 minute trip.

So I would not count on them keeping noise down, but also they cannot be very restrictive...
 

EllowViper

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Not sure if this helps since you have a side exhaust...apples and oranges. Tough issue trying to "keyboard" resolve. I have walked a mile in your shoes with my 01. Started with stock. Added Corsa catback with stock cats/stock headers. Sounded fine. Went catless with the Corsa...sounded like a POS broken down Dodge truck and LOUD. Added 20" dynomax straight through mufflers where the cats were. Didn't do squat and had terrible drone/resonance. Added el cheapo high flow cats ($49.00 each off EBAY) and took the dynomax's out. Sounded perfect...no resonance and at WOT it really screamed. (The Corsa guy stated their system is optimized to work with a little backpressure) Added Bellanger headers with my ROE install leaving the high flow cats and Corsa as is. Again perfect with no drone. Easy on the ears until WOT...and then PERFECT. So IMO, keep the Corsa, add the el cheapo high flow cats (no need to pay the big $$$ for random techs or any one elses). The Moroso guy is a "*****" and doesn't have a clue. Oh yea, on my Corsa, I go from a 3" collector/turnout into the 3" cats into the stock 2.5" Corsa connection that then opens up into the full 3" after the Corsa resonator. Not sure if the 2.5" step down helps with the drone/resonance, but I know you can get the Corsa with the full 3" connections. Not sure which one you have (probably the 2.5" if hooked to the stock cats)...but then again I keep forgeting you have a side exhaust...eegads.
 
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georgethedog

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Not sure if this helps since you have a side exhaust...apples and oranges. Tough issue trying to "keyboard" resolve. I have walked a mile in your shoes with my 01. Started with stock. Added Corsa catback with stock cats/stock headers. Sounded fine. Went catless with the Corsa...sounded like a POS broken down Dodge truck and LOUD. Added 20" dynomax straight through mufflers where the cats were. Didn't do squat and had terrible drone/resonance. Added el cheapo high flow cats ($49.00 each off EBAY) and took the dynomax's out. Sounded perfect...no resonance and at WOT it really screamed. (The Corsa guy stated their system is optimized to work with a little backpressure) Added Bellanger headers with my ROE install leaving the high flow cats and Corsa as is. Again perfect with no drone. Easy on the ears until WOT...and then PERFECT. So IMO, keep the Corsa, add the el cheapo high flow cats (no need to pay the big $$$ for random techs or any one elses). The Moroso guy is a "*****" and doesn't have a clue. Oh yea, on my Corsa, I go from a 3" collector/turnout into the 3" cats into the stock 2.5" Corsa connection that then opens up into the full 3" after the Corsa resonator. Not sure if the 2.5" step down helps with the drone/resonance, but I know you can get the Corsa with the full 3" connections. Not sure which one you have (probably the 2.5" if hooked to the stock cats)...but then again I keep forgeting you have a side exhaust...eegads.

Thanks! However, my Avatar is old... I am referring to my '98 GTS with the exhaust in the back, so knowing that do you have anything to add??? Right now I have Roe Hi-Flow Cats and a Corsa system behind that(both 3" starting at the elbow bend in front of the cat). Too loud at 2,000-4,000 rpms. Lots of drone. Thanks.
 

1TONY1

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I had spiral flows and also a can type dynomax on my car. It wasn't to loud and there was no drone. When I removed my cats it was loud and droaned on the freeway....the spiral flows went where the cats were. As for restriction ... normally quieter = more restrictive but the times in my sig were run with this set-up.
 

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