# choosing a header size



## LS2Baaahad (Jun 30, 2010)

I've see kooks has 1-3/4" primaries and 1-7/8" primaries which ones would be better? Future mods are TSP torquer v2 cam fast intake and TB combo from TSP with corsa sport exhaust! arty:


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## jpalamar (Jul 22, 2008)

1 3/4 unless you are going bigger cube or FI.


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## george g (Mar 26, 2009)

The 1 3/4 fit better also.


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## LS2Baaahad (Jun 30, 2010)

Ok thanks for the feedback!


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## fattirewilly (May 26, 2006)

LS2Baaahad said:


> Ok thanks for the feedback!


Both...stepped 1 3/4 to 1 7/8. Don't have em but these are what I'd buy 

Kooks "Signature Series" Stepped Headers 1 3/4" x 1 7/8" x 3" - 2004-2006 Pontiac GTO - Limited Quantity Sale! [K6700-KR] - $1,399.95$1,189.95 : MarylandSpeed.com- Your First Stop on the Way to Performance!


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## Poncho Dan (Jun 30, 2009)

I think 1 7/8" primaries would be the right size for a H/C/I setup on stock cubes.


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## GM4life (Mar 18, 2007)

jpalamar said:


> 1 3/4 unless you are going bigger cube or FI.


:agree

Too big you loose some velocity=torque suffers. Bigger is not allways better unless you got the cubes to back it.


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## svede1212 (Nov 1, 2005)

GM4life said:


> :agree
> 
> Too big you loose some velocity=torque suffers. Bigger is not allways better unless you got the cubes to back it.


True unless the RPM is really up there. It's about how much air is moving thru them. A bigger cube engine has more air at any given RPM. A smaller cubed engine can have that same volume/velocity of air but at a higher RPM. That's why you lose it down low with a smaller engine.


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## GM4life (Mar 18, 2007)

svede1212 said:


> True unless the RPM is really up there. It's about how much air is moving thru them. A bigger cube engine has more air at any given RPM. A smaller cubed engine can have that same volume/velocity of air but at a higher RPM. That's why you lose it down low with a smaller engine.


Yes. I explaned this before in a long post while ago. I refuse to do it again, I just make it short and sweet


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