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Old 09-11-2020, 02:04 PM   #1
Scooby Newbie
Member#: 503624
Join Date: Jun 2019
Default Cobb Catback Exhaust adding 20hp at 4k RPM?

Hi all, reading through the article below, it says that they manged to get some significant hp gains on a Subaru STI just from the Cobb catback exhaust throughout the dyno graph and around 20hp at 4k rpm. Does anyone know if this is accurate and achievable on a stock STI? I was under the impression catback exhausts on a stock STI doesn't really add any gains and only improves sound. Thanks!

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Old 09-11-2020, 03:19 PM   #2
Scooby Newbie
Member#: 493104
Join Date: Oct 2018
Chapter/Region: Tri-State
Location: PA

Catbacks generally do not add much power-if at all. You can attribute these horsepower gains to testing variables such as dyno, location, etc. Most power gains will come from a
less restrictive downpipe because this is where most of the exhaust restrictions on these cars are.
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Old 09-11-2020, 03:36 PM   #3
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Member#: 491095
Join Date: Sep 2018
Chapter/Region: SWIC
Location: New Mexico
2009 STi Blue


catbacks do flow more and a larger exhaust would allow for more top end flow...i would suggest look at more dyno's like suggested above to see how other factors affect the data
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Old 09-12-2020, 08:00 AM   #4
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Member#: 492422
Join Date: Oct 2018
Chapter/Region: Tri-State
Location: North Jersey
2011 STI


I guess if you are looking at actual hard numbers based on dyno plots and results then yeah. Like stated above i think this can also be attributed to testing on different types of dynos. When it comes to dyno results, there are so many variable factors that will dictate what kind of power the car will make at that time.

I wouldnt really look to far into this. Its just a catback we're talking about here. It doesnt make anything to write home about in terms of gains. Upgrading the down pipe and header is where the power is made on these cars.
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Old 09-17-2020, 02:38 PM   #5
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Member#: 477013
Join Date: Nov 2017
Location: Massachusetts
2019 STI Limited
Ice Silver Metallic


According to the article above they tested 12 different exhaust systems on the same dyno, same exact sti. Could it be possible some cat back systems do increase power?
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