DC2R JDM & AUDM oem exhaust differences

[rhys.l]

I've always been curious on the exact differences between the jdm and audm dc2 type r exhausts. I.e., exactly how badly we got jibbed. Today I had an almost complete set of each, so I took a few measurements whilst they were in bits. Could be useful as a future reference for some, or just for interests sake if you're a nerd like me

B PIPES

Length (flange to flange):
JDM ~195cm, AUDM ~183cm


(AUDM top, JDM bottom)

Inlet (ID):
JDM 50mm, AUDM 44mm


(JDM left, AUDM right)


(AUDM left, JDM right)

Outlet (ID):
JDM 47mm, AUDM 47mm

Pipe (OD):
JDM 180mm, AUDM 180mm

JDM b pipe (98 spec) has 3 resonators, AUDM b pipe has 2 resonators.

Summary: JDM b pipe is longer, has 1 extra resonator (98 spec), and has a larger diameter inlet. Otherwise, same.


CATS

Length (flange to flange):
JDM 304mm (12"), AUDM 447.5mm


(AUDM top, JDM bottom)

Inlet (ID, effective diameter not diameter at flange or donut gasket):
JDM ~61mm, AUDM ~47mm


(JDM left, AUDM right)

Outlet (ID)

JDM 50mm, AUDM 46mm


(AUDM left, JDM right)

JDM cat transmits more light when looked through. This could be because it is higher flow or just because it is shorter

Summary: JDM cat is shorter, has a larger diameter inlet and outlet


B PIPE AND CAT

AUDM system is slightly longer


(JDM top, AUDM bottom)


HEADERS - EK9, JDM ITR (98 spec), AUDM ITR

AUDM ITR next to JDM ITR headers:


(AUDM left, JDM right)

Horizontal length from flange to flange:
JDM ITR 463mm (EK9 same), AUDM 433mm

Inlets (ID):
JDM ITR 4-1 47 x 35, JDM EK9 46 x 33.5mm, AUDM 48 x 34mm


(JDM EK9 left, AUDM right)


(JDM ITR)

Outlet (ID):
JDM ITR 4-1 55mm, JDM EK9 55mm, AUDM 40mm


(AUDM left, JDM EK9 right)


(AUDM left, JDM ITR right)

Primaries (OD):
JDM ITR 136mm, AUDM 110mm


(AUDM left, JDM ITR right)

Summary: AUDM DC2R header is shorter, and has a significantly smaller outlet and primaries.

[90LAN]

96 spec itr b pipes only have 2 resonators
98 spec have 3 resonators to compensate for the louder jdm 4-1 exhaust manifold

rhys whats the size of primary comparisons

nice write up

[dorikin]

Always been curious about the exact differences.

Nice work mate

[EKVTIR-T]

This is what I like.

Straight info not hearsay

[rhys.l]

96 spec itr b pipes only have 2 resonators
98 spec have 3 resonators to compensate for the louder jdm 4-1 exhaust manifold

rhys whats the size of primary comparisons

nice write up

Thanks for the extra info Lan. What do you mean by the size of primary?

[Bludger]

wow, awesome post mate, well done.

[TGW92]

This is so awesome Rhys!

Can't wait to get my exhaust on now that I know heaps more about it

Thanks for the mad write up!!!

[Monetz]

nice post Rhys, what about UKDM and USDM r they the same?

[rhys.l]

Cheers for the comments!

Not sure about the UKDM and USDM exhausts. I'd say if those cars claim the same power as the AUDM type r (141kW) they would have something similar, or the same.

[skeptic_]

Very interesting, Awesome post!

What confuses me though is why header + cat + catback have all different ID inlets and outlets..
Like the JDM header =~55mm(2.2") outlet, JDM cat =~61mm(2.5") inlet with ~50mm(2") outlet, JDM b pipe =~50mm(2") inlet
What i dont understand is how they all bolt up perfectly if they have inconsistant piping size through the exhaust? Could someone please clear things up?
And i also thought JDM cat backs were 2.36" but the picture shows 2"?
Sorry for making things so complicated.. im the type of person that needs to know why things are a certain way :s

[rhys.l]

Hey mate,

There are two reasons why it all bolts up:

1) What I measured is the ID of the pipes. The flanges on either side of a join will be the same size and therefore the pieces will bolt together
2) Specifically for the header - cat join, there is a donut gasket which fits between and creates a snug fit

I'm not sure what the ID of the b pipes (if that's what you mean) are. What I measured above is the true diameter at the flange, where the pipes step down in diameter (i.e. bottleneck). I did measure the OD of both b pipes. Assuming the same piping thickness on both AUDM and JDM, the ID of the b pipes is the same. The only differences are as noted in the first post.

[tseesinngwailo]

Fantastic writeup, have been wanting to change mine for a while, and I have a friend that goes to Japan regularly, will ask him to get me a 98 spec JDM, so they go stainless and we didnt?? Gotta love the beancounters at Honda Aus..

Also, do you happen to have measurements of the exhaust from flange to bends etc? I have an aftermarket stainless catback one that I was thinking to use (amazing bends on it), but haven't got the time to pull mine off first, it looks like it matches, but I wont use the muffler as it has a 4 inch tip, on a DC2R that would be too ricey