4th Gen JDM Header pipe size?

[wurlycorner]

Just been under the front of the JDM looking at exhaust stuff and the front header pipes struck me as looking pretty large, so I measured them.

They're 2.25 (the 2 pipes in front of the collector and the pipe going into the front of the cat.
Measured the UKDM and the 2 pipes going into the collector are 2".

Is that standard size for JDM?
I didn't think they had larger header pipes, thought the only difference was tubular manifold rather than cast?


The bummer is, I'd originally bought a japspeed header to fit to the UKDM, but after getting the JDM I decided to put it on that and was going to swap the tubular OEM JDM onto the UKDM.
Measured the pipe size on the japspeed and it's 2" so that won't be going on the JDM now

[spudep91]

Yea we noticed that to pal the jdm appeared to be bigger. I think there dubbel skined though so will be smaller inside i think

[ADS1]

When i removed my jdm down pipe, i measured the pipe size internal, where they meet the mani.
Can't remember the exact size, but was less than 2".
They seem to get bigger towards the cat end, so maybe double skinned as spudep91 says.

[wurlycorner]

Ahhh... Interesting! Thanks for the response guys.
That might end up making sense, as practically the whole of the rest of the exhaust is skinned with heat-shields too.

So I might end up fitting this header to it then because it might not be a downgrade?

Does anyone have a JDM header/manifold off the car that they can take pics of or measure the actual (i.e. internal) pipe sizes of please?

Thanks!

[CrunchyAdams82]

JDM Manifold Hole Dimensions, as requested.









Hope that helps.

[wurlycorner]

Oh you're a star!

That's brilliant, thanks

+rep

[CrunchyAdams82]