restictive AUDM exhuast

[Berty]

^ -.- Berty said tinker!

[tinkerbell]

fark!

that is twice i have done that! sorry

[SpecJ]

check it out - for those not on ozhonda

the pictures speak for themselves. They look very close to vti-r headers.

JDM 4-1s vs AUDM 4-2-1s

[B.ITR.00]

the standard AUDM ITR headers are really really bad ay... what about the DC5 do they suffer the same restriction as the DC2 dose standard ?

[Nepolian]

the standard AUDM ITR headers are really really bad ay... what about the DC5 do they suffer the same restriction as the DC2 dose standard ?

Yep!

[PHATJM]

nice work jeff,

you'd feel the difference straight away, i had a set before which i never got to use

i kinda miss the quietness of a stock exhaust system

[SpecJ]

Here is the welding the exhaust shop did. they basically cut away all the 2" inlets and outlets frmo bpipe and jdm cat respectively and put nice wide pipe in. then reflanged the whole thing

as john said, i didnt really notice much at first but after driving a bit, i can say there are noticeable gains in terms of revs climbing faster, and the engine generally breathing and feeling a lot 'free-er'. I notice that vtec goes harder and louder, and low to mid has improved as well.

I've got the heatshields and everything put back on, and now it looks back to stock. awesome.

[EG30]

The stock aust spec B18c7 headers are such an abortion in terms of design and manufacture quality it's hard to believe it's made by honda. Even by sight you can tell the primaries are no where near equal length, wont be surprised if the non type R cast iron manifold are closer to equal length. As a result the motor idles bit lumpy/rough.

We couldnt believe the diff in idle smoothness when we switch to Toda headers + toda au fabricated xforce CAT. On top of that the car had way more driveablilty down low from idle onwards, despite way bigger primaries.

They are useful for some applications though, I now use them to stop my spare engine rocking on the ground after my 4-1 headers from that engine was sold.

[DC2RKID]

what about the standard cat ? is it a good idea to ditch it and get an aftermarket one....and is it iligel to change tyo a high flow cat if the car came with a 3 way cat standard

[EG30]

what about the standard cat ? is it a good idea to ditch it and get an aftermarket one....and is it iligel to change tyo a high flow cat if the car came with a 3 way cat standard

definately a great idea for flow and performance....

but....they are not ADR approved and for a good reason, it flows good but does f-all in terms of catalytic action and unlikely to pass a proper emissions test. We can smell unburnt fuel much more once we had the high flow CAT fitted be in on the driveway or following in another car.

my exhaust guy said high flow CAT has about 15-20% restriction, performance ceramic about 30-40%, factory ones 40-50%.

factory ones lot more restrictive and bigger for a reason, to keep the gas hot and spend lot more time in there for the catalytic action to work properly.

so it's your call, if you test diff setups I doubt if you want anything other than high flow metal cat and test pipe for the track.

[szymonsta]

i dont have the dyno plots handy, but i ran several combinations of exhaust on my dc2r:
1) stock
2) jdm 98model 4-1 (inc heatshield) , jdm 98model cat converter, fgk pg cat-back, stock ecu
3) Maximworks 4-2-1, jdm 98model cat, fgk pg cat-back, stock ecu
4) Maximworks 4-2-1, jdm 98model cat, fgk pg cat-back, Mugen N1 ecu
5) Maximworks 4-2-1, WedsSport cat, fgk pg cat-back, Mugen N1 ecu
6) Maximworks 4-2-1, WedsSport cat, fgk pg cat-back, stock ecu

from my experience, jdm headers+fgk pg were definitely an improvement over the stock system, particularly mid-top end. however, the Mbit headers were an even bigger gain over the jdm stock manifold, across the rev range improvements in power.
my conclusion would be 'do it right first time' and get a well designed aftermarket header - i'd get jdm bolt-on eg. mugen, maximworks, toda or jun, (something with 45mm primaries in my opinion).
unfortunately never got to dyno the car with the new wedssport cat, but butt-dyno did not feel much difference vs stock jdm cat tbh, though logic would say a high-flow brand new cat should make some improvement over a used stock item.

with Maximworks 4-2-1, jdm 98model cat, fgk pg cat-back, Mugen N1 ecu, there was about 10kw atw advantage over standard. (00dc2 has the graph somewhere..)

edit: p.s the car ran perfectly with stock ecu and all combinations of header/cat/exhaust (someone was asking about stock ecu with aftermarket exhaust before..) the mugen ecu just gave me more power and a lower vtec switchover, higher rev limit, which made it even more enjoyable.