How many of you are running a DC JDM header wit the 2.5 collect wit a high flow 2.5 cat with a standard exaust like the Apexi N1 which is not 2.5?. Im getting ready to purchase my header and will be faced with this problem so i was wondering how the set up performs and what problems it faces.

thanks.

 

im sure you'll feel some gain, but very minimal... basically its like putting a 3" filter onto a 2" pipe, compared to a 3" filter with 3" pipe. only so much air can flow.

 

I have the JDM DC w/ 2.5 Carsound cat and stock ITR catback. After putting the header and cat on, I immediately noticed a difference, and could actually feel vtec engage.....still I can tell that it may be holding back a little extra power. As of right now, I am very pleased with the set-up, but am going to upgrade to 2.5 custom exhaust with Magnaflow muffler after I am able to buy cams.

 

The N1 is 60mm which is around 2.36"

2.5" header -> 2.5" cat -> 2.36" exhaust isn't so bad.

There are a number of people with this application, and they say it's running strong.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DC4TEG &raquo;</TD></TR><TR><TD CLASS="quote">I have the JDM DC w/ 2.5 Carsound cat and stock ITR catback. After putting the header and cat on, I immediately noticed a difference, and could actually feel vtec engage.....still I can tell that it may be holding back a little extra power. As of right now, I am very pleased with the set-up, but am going to upgrade to 2.5 custom exhaust with Magnaflow muffler after I am able to buy cams.</TD></TR></TABLE>

Let me know if you ever upgrade and if you ever sell your ITR catback (since I want to do a cutout on my exhaust system)...then pm me. BTW: I have a 2.5 custom exhaust mated to my carsound cat with a magnaflow muffler. Hmmmm

NRG

 

who makes an aftermarket 2.5 cat-back?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Skunk2nR &raquo;</TD></TR><TR><TD CLASS="quote">The N1 is 60mm which is around 2.36"

2.5" header -&gt; 2.5" cat -&gt; 2.36" exhaust isn't so bad.

There are a number of people with this application, and they say it's running strong. </TD></TR></TABLE>

I agree but IMO 2.5 all the way to the rear will be better. Also depends on your motor's set up.

 

yea but i got to take things one thing at a time. header and cat now and keep going down my list till i get to a new exhaust. The one I have on the car now hasnt even been on the car for a year yet.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BLK99VTECR &raquo;</TD></TR><TR><TD CLASS="quote">who makes an aftermarket 2.5 cat-back?</TD></TR></TABLE>

Its a rarity to find one... there a guy on this board, kteller who does quality custom mandrel bends... check him out.

NRG

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Skunk2nR &raquo;</TD></TR><TR><TD CLASS="quote">2.5" header -&gt; 2.5" cat -&gt; 2.36" exhaust isn't so bad.

There are a number of people with this application, and they say it's running strong. </TD></TR></TABLE>

I had that on my JRSC'd GSR and made decent power, and have the same setup with a 2.5" DP & test pipe on my turbo'd GSR and its doing alright for itself as well.

I wouldnt sweat .14"...Id worry more about the design of the exhaust.

 

hmm i wouldnt mind getting s test pipe if that yerns the most power, but i wonder if i would get away with it.

 

right now i'm running a DC jdm 4-1 (installed last night ), 2.5" test pipe, apexi n1 catback (2.36"). All i can say is that its loud as hell. You can actually hear my vtec now, i didnt notice any lost in low end. Top end pulls much harder now, the rpms revv quicker than before. I'm going to install my carsound cat tomorrow, test pipe is too loud and stinks lol i'll use it for when i hit the track.

 

if you're serious about high hp numbers down the road... two words for most of you.

CUT OUT

-NRG

 

the n1 is 2.25 right?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gsrguy &raquo;</TD></TR><TR><TD CLASS="quote">the n1 is 2.25 right?</TD></TR></TABLE>

It's already been mentioned that it's 60mm.

If you want a bolt-on 2.5" system your options are SMSP, Hytech, Type One.

 

I gained 10whp and 10wtq in the mid range after putting my jdm itr header and j's racing intake. And im running the obx-r 2 1/4" cat back with the obx "high flow" cat. 98ctr.




Modified by 98ctr at 4:49 PM 1/30/2004

 

Most people dont realize it but a lot of aftermarket bolt-on exhaust have bottlenecks. Reasons why I go custom now.

https://honda-tech.com/zerothread?id=214169

 

what size is the Apexi GT Spec for Civics?

 

You're really losing out on potential power by bottlenecking down. You're creating backpressure.

It is okay to step up from say, 2.25 to 2.36, but stepping down is counterproductive.

 

where am i steping down from?

 

i think he means stock?

 

You said 2.5" collector on the header, 2.5" cat, and a 2.36" exhaust. You're stepping down the diameter.

 

well technically im not stepping down because the exhaust has already been on the car for almost a year. I will be STEPPING UP to the 2.5 header and cat

 

You're probably doing more harm than good. Buy the header and cat now if you want, but don't install them until you get a 2.5" b-pipe/muffler.

 

my bad, i didn't read it right.