Matt300

Well, it turns out my exhaust header is cracked! First question of the night, how the hell did I do that? I'll post pics tomorrow, as it's 1:41 AM here. The tuning shop I trust my baby too hasn't let me down ever, and we both agreed on a DC Sports 4-2-1. I've been having a few reservations about it though, such as:

1) I believe I get to keep the O2 sensors, but there was something about a Cat. Converter bypass too. Don't I need that to pass the yearly inspection? I live in Texas.

2) What would that do to emissions and MPG?

3) I suppose doing the header was going to happen anyway as I've been considering either nitrous or turbo down the line. It's a '05 LX. I already have custom piping w/ a HKS muffler, so with the header I should be taken care of exhaust-wise, right?

I was all for it at first, but I'm a little nervous (due to not knowing much about this particular subject) about swapping the header if it means I'm losing the cat. I'm also worried for the MPGs since I drive 23 miles to work and 23 back, highway (roughly 30 min.). And here's the kicker, in rural areas, some mail delivery routes have the postal carriers use their own vehicles. I get compensated for gas, of course, but it's a fixed rate. I like getting $30 for the $6 I use in fuel. I'd like the power gain even if I'd be losing a few MPG, but it's not THAT big a drop in fuel economy, right?

Many thanks to the answers that will follow. You guys have always given the best advice when it comes to my Civic!

gearbox

iTrader: (95)

its very common for dx/lx header (with built in cat) to crack from all the heat/cold cycles. if you go with the dc race header, which is a very nice piece, you will lose the cat converter. a better option if you have the $$ is convert to the full EX exhaust system. ex header, ex downpipe, ex cat, and ex catback with muffler.

sdaidoji

iTrader: (1)

my understanding is that 4-2-1 loses the cat and 4-1 will keep it

Matt300

Any chance of being able to fix that with another High-Flow Cat? I just recently gashed my exhaust pipe, so I replaced it with a custom pipe and a HKS muffler. I think all that's really left is the header.

@sdaidoji, would you happen to know if there's a noticeable diff from the 4-1 and the 4-2-1?

I've been trying to read up on it, so I think I've come down to a few options. Would it be possible to get a high-flow cat and use it with the 4-2-1? Next option would be to get a 4-1 if there's not too much diff in performance, and then I wouldn't have to get the cat. Next option would be to just do a 4-2-1 and nix the cat and hope the Cat Bypass. Lots of ways to go, which is what makes this a little confusing.

gearbox

iTrader: (95)

most hi flow cats are garbage and you wouldnt even pass emissions. they have a very short life and dont work like oem.

sdaidoji

iTrader: (1)

No idea, I stopped searching about our headers, most of them does not seem to give much gains unless some other heavier mods like cams are present.
I do believe cat or no cat matters much more than 1/2 hp if you need to pass inspection.
Ask your shop about differences?

Edit - I just saw you have an LX...
Do a ex conversion first and foremost, and forget power gains...

01EX5speed

im new to this forum and just bought a used 01 Ex 5speed...im just wondering whats so good about the ex full exhaust? sorry if this is in the wrong area..thanks

Balzdpr

What, What , What???? What the hell are you guys talking about I have an EX and that exhaust cat and header are crap. I mean major ****. Are you all refering to a custom joby or a bolt on replacement option thats for an EX and gives you Pa-Pa-Pa-Power. Cause im in the market for a Header as well. I have an after market exhaust and custom made pipe from the cat to that exhaust. The pipe, coming from the cat is like all shrinked down like some shity looking football because the custom pipe is bigger in diameter than the outlet of the cat. The f-ing cat rattles like **** sometimes and frankly I could see it disapear. Anyhow, clarify what you'all talkin about cause I confused.

sdaidoji

iTrader: (1)

ah, OK, you were thread jacking - i saw Matt300's car - The OP of this thread :P

Matt300

Ok, so I've been looking around based on the advice so far and here's what I came up with. Let me see if I'm understanding this right. My setup would have to go something like this:

DC 4-2-1 Header -> EX Downpipe -> EX Cat -> Attach to custom pipe/HKS Muffler from previous repair

Does that work? I need to check my stuff again, but I'm sure that's a 3" on the muffler. I'm finding I'm a lot more comfortable going the EX route again vs. losing the cat. In case push comes to shove though, could I just do the DC Header, bypass the Cat, and hook it up to what I've got now? That crack in the header expanded a little faster than I thought, so I really need to get that taken care of. If I need to, maybe I'll just do the header for now, pay that off, then go for the rest of the setup.

gearbox

iTrader: (95)

im not completely sure, but i thought the dc 4-2-1 header for the ex replaces the downpipe and cat.

Balzdpr

Im pretty sure what your discribing is the "racing header" as that device does delete the cat and does make your car non steet legal. You will not get a legal inspection sticker with it.
I have done alot of research on this subject and have found out that the only people who really know are those who have replaced the whole assemply in one big swap (head to tip). So as of now Im friggin confused super bad.
I know, because I have an EX- that the escape pipe out the back of the ex cat is far less in diameter than any pipe you could buy or want to buy for performance or sound gains. In my opinion you are better off going with the racing header which does bypass the cat or by purchasing a two piece system that offers a high flow cat system.

Matt300

http://www.dezod.com/pd_dc_sports_41...ic_ex_01up.cfm

Ok, I see what you guys are saying about it, I didn't see the big pipe, so that would make it really hard to keep a cat in the system.

How's about that 4-1 that I put in the link? It looks like just the header, so I should conceivably be able to do the header, then pop in the stuff from the EX system, right?

gearbox

iTrader: (95)

yeah dc 4-1 header for the ex, then the ex downpipe, ex cat, and ex catback.

Matt300

Sounds like a plan! I just found a 4-1 header from a local performance shop for a little over 200 bucks! Now all I have to do is hunt down the stuff for the EX!

I'll let you guys know how it goes. Thanks for all the input! I think I'll be much happier with the EX and Cat vs. bypassing the Cat sensor.

Matt300

Here's the pics from the header I have on now:



Here's the plan so far:

1) DC Sports 4-1 Header for the EX

http://cgi.ebay.com/ebaymotors/DC-SP...item519620fcee

And that should attach to #2)

http://cgi.ebay.com/ebaymotors/Honda...item2a13d438e8

Not sure if that's the right downpipe (or a good one at that, opinions?), but that's what I got when searching for an EX downpipe.

After that, attach to #3)

http://www.procivic.com/pages-produc...513/index.html

I found in another thread yesterday that it's best to get a cat with the sensor in the middle. I'm looking at the semi-direct fit option from that website since it's got the O2 sensor bung already there. What's throwing me for a loop is the universal fit (which needs a bit more cutting/welding to get it all together) comes in different inlet/outlet sizes. Would I need one of those bigger ones since my pipe is bigger than stock? After I pick my cat, then I just have them make it fit to the rest of my pipe, right?

Not sure if it helps, but here's what it looks like under my car right now.

Here's where my stock header/cat/pipe comes down and joins the part I had repaired.



And continuing down the car....



Further down...



And ending with the HKS Muffler





Really, thanks for putting up with all the Q's. Just wanna make sure that I'm doing this right before I order a couple hundred bucks worth of parts that I'm not going to be able to use.

gearbox

iTrader: (95)

i would strongly recommend sticking with the ex honda oem cat converter. or at least pick up a used one with less than 50k miles. that downpipe is sketchy as well. stick with oem or maybe megan racing.

Matt300

I tried looking around for OEM at Majestic Honda and Honda Parts Unlimited, and it looks like the downpipe and cat come together. The diagrams don't show the cat by itself, so I'm assuming it's attached to the pipe? So if I went OEM, I don't have to worry about finding a downpipe, right?

gearbox

iTrader: (95)

yes its a one piece, $800 for the cat and downpipe. if that seems expensive, it lasts over 100k miles unlike the cheapo aftermarket versions.