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Discussion Starter #1
i currently am driving a 2000 civic dx and recently bought a 2.5 inch catback and once i got into it i found it was not long enough aparently all models but the EX have the cat built into the stock exhaust manifold so the DX downpipes are much shorter than the EX's which leaves a huge gap in you exhaust where normaly on an EX the cat would be so this is my solution to that problem until i get an aftermarket header and test pipe let me know if you think im crazy or if this is legit....keep in mind this is my first build and today is my first day as a member haha



this end will bolt up to the aftermarket cat back i plan to weld it to the stock pipe after i cut it to length if some of you are familiar with this problem you may know what my plan is but if not i plan to finish it tonight and will post more pictures
 

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89 CRX Si
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That will work and prevent exhaust gasses from leaking, but it will cause some serious issues with flow. Each one of those "steps" is pretty severe, and the exhaust gasses will tumble as they flow from the smaller diameter pipe into the next step up...especially with the immediate (not gradual) increase in pipe volume. This creates turbulence, which actually blocks exhaust gas flow (shrinks the effective inner diameter at the junction by about half...which is significant).

A better design would be more gradual...a cone would even be better.

That being said, that is a quality built piece...especially if this is your first build. I rep you for that if nothing else.
 

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Discussion Starter #3
yea what your saying about the sudden change in pipe diameters is right but if i was to start making these i would use 2.5 inch piping all the way with no diameter change to another custom exhaust flange to eliminate that problem now that i have built one i figured out how i can fabricate them better to work out all the kinks but thanks man
 
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