i've searched for this stuff but only found info for 2.5"
If i were to get a 4-1 (2.25") dc header + a 2.25" blank carsound cat + 2.25" mendrel exhaust piping...

what bolts/gaskets do i need for my connection to header + cat and cat + exhaust piping considering no gaskets/bolts came with the components....

i know i'll have to go to a muffler shop to get the flanges put on...

i have a 99 gsr....there's no o2 sensor on the header but there is one on the cat right?

 

If you get the flanges put on the cat done at a muffler shop. They'll have all the gaskets there for your exhaust.

There are two 02 sensor bungs on the cat. One in the front and one in the rear.

If you buy a decent header/exhaust, it might come with bolts, and gaskets.

 

the dc 4-1 is actually a 2" collector, but there are no 2.25" collector headers for our cars that i know of.

You will need a new stock header -> cat gasket, and cat -> exhaust gasket. Both should be readily available at the dealership.

FOr a little more money you can get a premade carsound cat that has the flanges and o2 sensor bungs.

I beleave you have 2 o2 sensors in your cat.

 

are you serious.....there's no 2.25" header collectors? the dc 4-1 isn't 2.25"?

 

nope, its 2"

 

not to be a dick or anything....but i always had the impression that the dc had 2.25" collectors?

so these people really didn't have 2.25" collectors or are they talking about something different...?

https://honda-tech.com/zerothread?id=405828
https://honda-tech.com/zerothread?id=217968
https://honda-tech.com/zerothread?id=189486

 

Its a common mistake. The only reason they bolt up to the stock cat is because they are 2" collectors.

The stock cat only has a 2" inlet, and you use the stock 2" doughnut gasket as well.

People probably figure they are 2.25" because the smallest exhaust that is readily available is 2.25".

As far as I know there are no 2.25" collecters for our engines unless you go custom.

Let me try and find some pictures of measurements.

edit: the picture I was looking for was deleted unfortunetly. But the stock cat is with out a doubt 2" ID. There is no way a 2.25" OD collector would mate up properly to a stock cat, and I assure you the DC sports has no trouble. I have measured it myself, the OD was 2" and the ID was about 1.8".

People just assume its 2.25"

 

do you think it would be a good idea to match it up with a 2.25" carsound cat with 2.25" exhaust piping into a comptech muffler or should i just stick with the stock cat with the 2.25" exhaust?

 

With out a doubt go with the carsound cat.

The stock cat not only flows only 216cfm (or so), it also is very small and becomes a huge bottleneck when matted with other exhaust components.

The exhuast has to work together as a system to evacuate gases quickly, and provide scavanging.

The stock cat has a 2" inlet and a 1.8" outlet. Very small when mated with a 2.25" or larger exhaust. Go with the 2.25" carsound.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by iLUVmySH &raquo;</TD></TR><TR><TD CLASS="quote">do you think it would be a good idea to match it up with a 2.25" carsound cat with 2.25" exhaust piping into a comptech muffler or should i just stick with the stock cat with the 2.25" exhaust?</TD></TR></TABLE>

Are you getting the Comptech 2.25" b-piping or a different brand to attach to the Comptech muffler?

Keep in mind that you'll want to be on the look out for the b-pipe flange bottleneck that most aftermarket cat-back exhausts have.
For example: I have the 2.25" (measured on the inside diameter) Carsound cat mated to the Comptech cat-back which is 2.25" (measured on the outside diameter...that translates to 2.14" on the inside) so you're already stepping down slightly. It gets worse because the flange that most of the aftermarket companies use tapers down even further from the 2.14" inside diameter down to 2".
A quarter of an inch is a pretty sizable bottleneck.
I'd recommend clipping that flange and getting a true 2.25" ID flange that gently tapers down to the 2.14" ID of the rest of your 2.25" system.

And for the record: StyleTeg is 100% correct in what he told you about the header collector sizes. There are no 2.25" collectors unless you go w/ a custom header builder.
HTH

 

I sent an e-mail to DC sports regarding the 4-2-1 header for a non-vtec integra and was told the collector outlet was 2.25 inches.......I've got a test pipe on right now ( 2 inch inlet and 2.25 outlet to 2.25 inch costom piping ), and was worried the header would not correctly bolt up to the 2 inch inlet on the test pipe, so according to the above posts, I should not have any problems? I've got a 2.25 in and out carsound cat that i'm waiting to install, but since it has to be welded, I'm still waiting to get my header and have it installed before a shop welds the cat in place. The test pipe CEL's are killing my gas mileage......

 

You will be fine. My dc 4-2-1 header had no fitment issues with my 2" cat or 2" testpipe inlet.

I have measured the collector myself and it is 2", the dc sports representative was no doubt trying to make a sale. Bigger sounds better to most people.

The o2 sensor in the cat doesn't actually effect a/f, its more of a monitoring tool for the health of the cat. If you don't like the CEL, o2 sims are pretty easy to make.

 

if i decide to get the carsound cat put on, would i have any problems considering the .25 inch difference between the collector outlet and cat inlet????

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jamessh1 &raquo;</TD></TR><TR><TD CLASS="quote">if i decide to get the carsound cat put on, would i have any problems considering the .25 inch difference between the collector outlet and cat inlet????</TD></TR></TABLE>

No.
There are no problems performance-wise because you're stepping up in diameter.

There are no problems fitment-wise because the flanges on a 2.25" cat inlet will bolt up to any usdm header (2" collector). On the outlet for the cat, the flange should fit any thing from the stock 1.9" system all the way up to a 2.36" cat back systems.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StyleTEG &raquo;</TD></TR><TR><TD CLASS="quote">
I have measured the collector myself and it is 2", the dc sports representative was no doubt trying to make a sale. Bigger sounds better to most people.
</TD></TR></TABLE>

The DC (as well as all the other headers w/ 2" collector) may in fact measure 2.25" somewhere along the a-pipe. The exit/collector diameter is what we're after. DC knows the difference between the two locations and like Style said was probably trying to make their header stand out from the pack.

We had this same debate on Team-Integra a few months ago from a RSR header owner who insisted that he had a 2.25" collector because thats what he was told. He finally took the header off and measured it like we asked and sure as ****........2" exit just like all the other USDM headers.

To companies who conveniently mis-quote specs for their product

 

I guess we all learn something new everyday. I personally had no idea that there isn't a 2.25" ID collector. So, it's either 2" or 2.5" which is a big step. Now I see why non-VTEC motors work better with the 2" collector and the VTEC motors work better with the 2.5" collector.

who wonders how an LS motor would respond if someone would make a properly designed 2.25" collector header.

 

so me running a 99 gsr with just i/h/e/cat i should be running 2.5"????

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BlueTeg &raquo;</TD></TR><TR><TD CLASS="quote">

Are you getting the Comptech 2.25" b-piping or a different brand to attach to the Comptech muffler?.....
HTH</TD></TR></TABLE>

no i'm not using the comptech piping....i'm going to a muffler shop and have them put on some 2.25" mendrel bent piping for me

 

If you're just going with i/h/c/e......then a 2" collector will be just fine. If you ever plan on upgrading cams or souping up your internals for more compression/power than I would definitely go with a 2.5" for your header/cat/exhaust.

Don't be fooled by the JDM hype meisters who insist that to get good gains out of a B18c you have to go with one of the JDM headers/2.5" collector.

The Great Header test is a perfect example that a usdm 4-2-1 header with 2" collector (in this particular case, the Comptech street header) flows adaquately in comparison to the larger JDM headers. And keep in mind that was on an ITR which makes more power and breathes harder than a GSR (all things being equal).


Peak Numbers: 186 whp, 135 tq



Peak Numbers: 187 whp, 137 tq

To see how the rest of the headers tested go to:
http://www.daliracing.com/v666...t.cfm

You can bet the larger headers with 2.5" exits would start to really pull away from the smaller Comptech header once you start swapping internals and/or tuning that ITR.



Modified by BlueTeg at 4:29 PM 5/11/2003

 

thanks for all your great info and help for everyone who has answered my thread esp. blueteg and styleteg

 

what is the comptech collector, 2"?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Scary1109 &raquo;</TD></TR><TR><TD CLASS="quote">what is the comptech collector, 2"?</TD></TR></TABLE>

yup!