CAT Comparison


elchunk

elchunk

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Well as so many people seem to get confused as to what the differences are between a UKDM and a JDM catalytic converter actually are i though what better answer that to post up a picture comparison! (UKDM on the left and JDM on the right!)

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UKDM CAT:
Flange to flange - 16 1/2 inches
Collector diameter - 2 inches
exit diameter - 1 7/8 inches

JDM CAT
Flange to flange - 12 inches
Collector diameter - 2 1/2 inches
exit diameter - 2 inches
 

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Last edited:
Good post!
State the specs also,ukdm 2.25" collector and approx 17" in length.
Jdm 2.5" collector and approx 12" in length.

The opposite end with 3 bolt pattern for b pipe are exact same between ukdm and jdm.
 
the opposite end on the cats differ slightly but not as much as the collector. I'll get some more photos up with measurements and descriptions. :nice:
 
sorry to be dumb...
Am i right in saying the EK9 was only sold as JDM version..
If so which car did the UKDM cat come from.... EK4???... surely that would explain the different size.

Reason i thought this is surely an EK9 with a UKDM cat would make less power due to difference in diameter piping.

tell me if i'm wrong..
 
I meant the b pipe will fit to either jdm ot ukdm cat exit as bolt pattern is same but yes the
Diameter does differ slightly.
As for people saying the jdm collector is 2.25 instead of 2.5 well we all know thats a "grey area".
 
yea its not quite 2.5 inches say closer to around 60mm which is about 2.36 inches!:naughty:

I done this thread so poeple that buy JDM systems for their ek4 ej9 etc... can understand the difference in length and not get confused and understand whats going on when people say to get a jdm length decat etc...
 
ok here the thing i have a stock civic ek4. i want to put on a 98 spec dc2 jdm manifold. will i need the jdm cat also. and will the jdm cat make littie more power than the uk 1.
 
owww helpfully ness here ! , i want a decat for my standered system isit best to get an adjustable one or the correct 12" decat ?

im also going to be running a buddy club system in the future so would it be wise to get the adjustable ?
 
davidglanza said:
So will a 98 spec mani with 2.5 adjustable decat line up with my ukdm dc2 exhaust fine?:)
Click to expand...

if the adjustable decat goes to udm length then yes.

ek9-Dez said:
owww helpfully ness here ! , i want a decat for my standered system isit best to get an adjustable one or the correct 12" decat ?

im also going to be running a buddy club system in the future so would it be wise to get the adjustable ?
Click to expand...

Depends what the buddy club system is for (JDM or UKDM), would be a safer bet to just get the Adjustable decat. that way you know it will fit.
 
Rep added.....very helpful! Trying to explain this to people when i have been looking to buy a system has been a nightmare!! You ask if its ek4 or ek9 fitment and they say both......:angry2:

I took off my ek4 manifold for an ek9 one, bigger diameter, means bigger collector on cat/de-cat BUT the length of the down pipe is the same :naughty:

So the fact the cat/de-cat is different lengths means the difference in the length is taken on/off the centre section!!!! So yes they fit both with the diameter but the length of cat/de-cat will be unknown until you fit it :wow:

If we can get a manifold comparison pic and cat back would be awesome! I might be able to do ek4 vs ek9 cat back depending on what the system is made for when i receive it :nice:
 
keithiesbig1 said:
If we can get a manifold comparison pic and cat back would be awesome! I might be able to do ek4 vs ek9 cat back depending on what the system is made for when i receive it :nice:
Click to expand...

I could have done both manifold and system comparison, but had to sell my Manifold and EK9 system last year when i was out of work! :((
 
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