Catback HP increase??
Thread Starter
Tech Contributor
Joined: Mar 2003
Posts: 12,094
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Catback HP increase??
I'm not dropping money on noise but if you get any power from a catback witin reasonable noise limitations I will go for it. Anyone have confirmed gains with dyno testing solely for a catback?
I have kooks headers and don't want to have the bottleneck of the stock exhaust if there is a power difference.
I have kooks headers and don't want to have the bottleneck of the stock exhaust if there is a power difference.
Drifting
Joined: Aug 2004
Posts: 1,532
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Originally Posted by SpinMonster
I'm not dropping money on noise but if you get any power from a catback witin reasonable noise limitations I will go for it. Anyone have confirmed gains with dyno testing solely for a catback?
I have kooks headers and don't want to have the bottleneck of the stock exhaust if there is a power difference.
I have kooks headers and don't want to have the bottleneck of the stock exhaust if there is a power difference.
for the corsa sports with my kook's.How do you like the stock exhaust with the headers? Is there a better tone?
Drifting
Joined: May 2002
Posts: 1,530
Likes: 1
From: Houston TX
Originally Posted by archtop
I was told maybe gaining 3 hp for the corsa sports with my kook's.How do you like the stock exhaust with the headers? Is there a better tone?
for the corsa sports with my kook's.How do you like the stock exhaust with the headers? Is there a better tone?
Drifting
Joined: Aug 2004
Posts: 1,532
Likes: 0
Originally Posted by aggie88
I have heard on the forum the gain is ZERO (3 hp for $1000 is pretty much ZERO). What about HP increase from your Kooks?
Team Owner
Joined: Aug 2003
Posts: 38,314
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Originally Posted by haljensen
350 RWHP with homemade Magnaflow "catback".
365 RWHP with added Dynomaxx 1 7/8" headers.
365 RWHP with added Dynomaxx 1 7/8" headers.
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Racer
Joined: Feb 2005
Posts: 320
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From: San Jose CA
Originally Posted by aggie88
I have heard on the forum the gain is ZERO (3 hp for $1000 is pretty much ZERO). What about HP increase from your Kooks?
This is what I've been seeing. Either something like 3-5 rwhp or none at all. To be frank, a 3-5 rwhp increase is awful hard to prove since that much hp swing on a 400hp car can be simply dyno variance from pull to pull.
Here's the bonus question: What do you guys think about an after market exhaust AFTER you optimize out the entire flow path before it? I'm talking AFR heads, FAST 90 intake, big cam, quality LT headers. I think after you do all these, perhaps the aftermarket catbacks will make a much bigger difference.
Thread Starter
Tech Contributor
Joined: Mar 2003
Posts: 12,094
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Interesting point: a modded car will benefit more from air cleaners and exhaust flow.
The kooks are awesome sounding with the stock catback but not much volume change.
My car needs a tune bad but no way to do it myself yet and I'm not getting it done by a tuner twice. I am waiting for the big cam until i get the software.
The kooks are awesome sounding with the stock catback but not much volume change.
My car needs a tune bad but no way to do it myself yet and I'm not getting it done by a tuner twice. I am waiting for the big cam until i get the software.
Race Director
Joined: Mar 2005
Posts: 10,399
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From: Austin Texas
EB20003 & aggie88; Sorry, no base dyno, I'm guesstimating 340RWHP, seems to be on the high side of dyno runs I've seen. Hard to believe that I got as much as 10RWHP from the 2 1/2" mufflers but it's either that or believe that I had 350RWHP stock and gained nothing from the Magnaflows. Common sense says free flowing exhaust = HP, by going to a 2.5" in and 2.5" out smaller muffler with fewer baffles I increased flow (and HP?). I have the Lingenfelter CAI on order and will dyno again when it's installed.
Le Mans Master
Joined: Aug 2000
Posts: 5,529
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From: Austin Texas
Dyno results show that dynoing before, then removing the cats and dynoing again is right at the noise floor of the dyno (3-4 HP) --it could gain power, it could be break eve, or might even sho a small loss. However, the gain is very small.
On the other hand, heders reall do show power gains significantly above the noise floor of the dyno, and with some intake modes, even som more.
And then there is that $10,000 fine if you get caught without cats.....
All, in all, put the money into headers and intakes!
On the other hand, heders reall do show power gains significantly above the noise floor of the dyno, and with some intake modes, even som more.
And then there is that $10,000 fine if you get caught without cats.....
All, in all, put the money into headers and intakes!
Drifting
Joined: May 2002
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From: Houston TX
Originally Posted by Virt
Here's the bonus question: What do you guys think about an after market exhaust AFTER you optimize out the entire flow path before it? I'm talking AFR heads, FAST 90 intake, big cam, quality LT headers. I think after you do all these, perhaps the aftermarket catbacks will make a much bigger difference.
Racer
Joined: Feb 2005
Posts: 320
Likes: 1
From: San Jose CA
Originally Posted by aggie88
IMO - Yes! The ol' "engine is an air pump" analogy - unless the factory exhaust can flow more volume than needed for the 400hp.
That's kinda what I figured. A catback will be my very last upgrade if it ever comes. I would like my car to sound stock. But I plan to do everything else possible while staying N/A. But I've been seeing people just replaceing the mufflers with after market mufflers for something like 300 bux including labor. At that price I could afford to experiment a bit when all the other mods are in
Drifting
Joined: May 2002
Posts: 1,530
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From: Houston TX
Originally Posted by Virt
That's kinda what I figured. A catback will be my very last upgrade if it ever comes. I would like my car to sound stock. But I plan to do everything else possible while staying N/A. But I've been seeing people just replaceing the mufflers with after market mufflers for something like 300 bux including labor. At that price I could afford to experiment a bit when all the other mods are in
http://forums.corvetteforum.com/show....php?t=1161017
Drifting
Joined: May 2005
Posts: 1,254
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From: Ft. Liquordale Florida
I did 343 with SuperMaxx/Stinger/GHL's before tune, 371 after (and it was a conservative tune). Most "bone stocks" on the same dyno were doing between 328 & 335 - so by that assumption, the above mods net'd me about 10HP. The tune got me almost 30 more. Average "bone stocks" plus tune are getting somewhere around 345-350. I doubt that cat-backs in-&-of-themselves are really netting much in the way of HP gains, but as part of a system they certainly do help.
Beware though - regardless of claims of drone, the in-cabin decibals will rise considerably with the addition of any cat-back. I'm going to dynamat my rear trunk "bucket" sometime in the next week or two, to try and make the interior more livable. I love the bad-*** exhaust sound (and the car definately turns more heads now), but I want the quiet comfortable ride that I bought this car for too.
Rick
Beware though - regardless of claims of drone, the in-cabin decibals will rise considerably with the addition of any cat-back. I'm going to dynamat my rear trunk "bucket" sometime in the next week or two, to try and make the interior more livable. I love the bad-*** exhaust sound (and the car definately turns more heads now), but I want the quiet comfortable ride that I bought this car for too.
Rick
Melting Slicks
Joined: Jul 2001
Posts: 3,284
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From: Southwest Florida
As I remember, Vette magazine did before/after dyno runs with the Corsa Touring and got about 13 RWHP (12.9 I think was the number) on an otherwise bone stock C6. I don't remember which issue and it seems my "better half" threw away all my back issues. 
YMMV I guess, but it seems like the cat back systems do give you something.
Mike
YMMV I guess, but it seems like the cat back systems do give you something.
Mike
Melting Slicks
Joined: May 2005
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From: Stuttgart
Originally Posted by haljensen
350 RWHP with homemade Magnaflow "catback".
365 RWHP with added Dynomaxx 1 7/8" headers with high-flow cats.
365 RWHP with added Dynomaxx 1 7/8" headers with high-flow cats.
Team Owner
Joined: Jun 2001
Posts: 26,714
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From: Houston, TX
There was an article in "Vette" magazine (Oct 2005) that showed 9 lb ft of torque (peak) and 10 rwhp (peak). Low rpm gains were as much as 20 lb ft of torque. I am the first to admit that this goes against most of what we hear on the forum, although the truth is that there are very few before and after dyno runs on just exhausts.
BTW, this was a done at an independent shop in Ft Meyers Fl (Pro Auto Tech). If you read the article, it says that even the "hard core cynics" at the shop were surprised and impressed.
BTW, this was a done at an independent shop in Ft Meyers Fl (Pro Auto Tech). If you read the article, it says that even the "hard core cynics" at the shop were surprised and impressed.