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Power gains from catted y-pipe to open headers with extensions?

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Old Aug 29, 2005 | 06:26 PM
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Default Power gains from catted y-pipe to open headers with extensions?

Mods in the signature. Making 455 rwhp and 402 rwtq through a Kooks catted y-pipe and single 3" exhaust, 3" cutout and SLP Dual Dual. I've seen cars at my power level pick up a large amount of torque in the mid-range and top-end power by ditching the closed exhaust with cats and go open headers with some header extensions.

How much power/tq do you think I'd stand to gain? What would be the best length of the extensions? This is purely for a racing application as I mainly plan on running closed exhaust at any other time.
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Old Aug 30, 2005 | 06:52 AM
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Twelve hours and no ideas? Let's bump to the top.
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Old Aug 30, 2005 | 08:29 AM
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Do you plan on swaping the CB for the extentions every trip to the track or for other racing applications, and then go back to the CB when your finished?? Are you going to run rear o2's? The most common I've read about is 18" extentions. I going to say a 10/15 hp/tq gain.
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Old Aug 30, 2005 | 08:43 AM
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Originally Posted by conan
Do you plan on swaping the CB for the extentions every trip to the track or for other racing applications, and then go back to the CB when your finished?? Are you going to run rear o2's? The most common I've read about is 18" extentions. I going to say a 10/15 hp/tq gain.
That depends entirely on how much I gain by going to open headers. If I gain less than 10 rwhp/rwtq, then it's probably not worth taking off for the track (except for weight savings). But if the gains are 15-20, then I'll either run it at the track with open headers or I'll look into designing a better catback.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.

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Old Aug 30, 2005 | 09:53 AM
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How well does the DD flow compaired to the magnaflow/hooker/gmmg, ect?
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Old Aug 30, 2005 | 10:45 AM
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From what I've seen, the DD flows very well up to 500 rwhp. Pretty close in line with the mufflers you mentioned, just a lot quieter.
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Old Aug 30, 2005 | 10:47 AM
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I think you will pick up 30hp
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Old Aug 30, 2005 | 10:52 AM
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I'll guess ~28rwhp in the mid range and 23 peak...
*just a wildcard*
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Old Aug 30, 2005 | 11:03 AM
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That sounds like a huge amount of power difference. Don't know if my current exhaust is that restrictive...maybe? Anyone have any before/after dynos to show the gains?
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Old Aug 30, 2005 | 11:06 AM
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It seems like your current combo loves exhaust flow though, with the gains with switching to a 1.75 set of kooks and a catted Y you gained alot of power.. Only reasoning for my high guess. You may not gain as much on the top end, but the higer midrange will be greater it would seem.
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