Holden Performance Australian LS1 Powered Vehicles

Hsv shorty headers vs kooks

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Old Dec 24, 2024 | 11:06 AM
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Default Hsv shorty headers vs kooks

Ok, my current setup is kooks 1-7/8 to 3" headers to 3" cats to wma out at 2.5" then zl1 mufflers.

My plan is to swap to hsv 1-3/4" tri-y headers that have a 2" collector, then 2.5" cats, 2.5" resonators, and 2.5" xpipe out the zl1 mufflers.

The 2" collectors has me worried, or should I be fine?
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Old Dec 24, 2024 | 12:58 PM
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I'm going to GUESS that torque increases EVERYwhere under 4000 rpm, horspower peaks earlier, and nosedives after 5600 rpm.
If we are talking about your 415 cubic inch motor, I'll guess you lose 50 peak horspower
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Old Dec 25, 2024 | 12:00 AM
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Its funny how you should say that, I lost 50+ hp goin from 1-3/4 kook headers to 1-7/8.

And I pleaded with Kooks for a 1-3/4" headers but repeatedly they said they have discontinued this and only do the1-7/8
I could go with stainless Works but that's an additional $1500 for a gamble and then I have to redo my exhaust because the kook headers are slightly offset from each other versus stainless works are parallel
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Old Dec 29, 2024 | 07:15 AM
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Good news, I found I have the smaller headers from HsV. I am currently in talks with a guy with the correct 2.5" flange.
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Old Dec 29, 2024 | 09:04 AM
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Why not get a different brand 1 3/4 header? What vehicle is this? Conventional wisdom says 1 7/8 makes slightly more HP everywhere.
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