Gutted cat stock header vs aftermarket catless header NA application
 

Has anyone verified there is gains with aftermarket? The only thread I've seen is with a innovate SC kit and the stock gutted header was equal to the aftermarket header.

This has got me thinking the stock headers are probably a good design and the hp/tq gains come mostly from not having a cat?

I know in theory you should gain some more from runner length optimization, etc. but any real evidence?

Think the evidence is in the variation in aftermarket headers gains. There may be some hp lost by the stock cat, but the reality is there's much more left on the table from optimizing the design.


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Curious about this as well, with the current demand for aftermarket headers, there's bound to be a surplus of OEM headers floating around out there. Interested in what a set of 'optimized' stock headers could do...

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There is a one make race series in NZ where they remove the CAT and replace it with a nicer collector but i think the real advantage comes from being able to run a more aggressive tune.

I agree 100%. The extra power comes from the tune and lack of a cat much more than the header design. Since the stock header is a good design t begin with. Someone prove me wrong.

Wow I just got flamed for asking the same thing . its my understanding its about 5hp diff

Ignore my last post . I'm a dumbass

local shop near me cut out the cat in the header on his car used a full exhaust and put it on E85 and passed 200WHP with no issues.

I'm to try the same thing before I buy a header.