Emission Passing Headers

[01elantra4dr]

I'm thinking of getting headers, but i need both catalytic converters to pass emissions. That means i will keep the stock exhaust. Is it pointless to have stock exhaust with headers? I mean will there be any improvement in HP?

[Gregster]

Isnt the exhaust header and 1st catalytic converter 1 piece? If you need both cats, why dont you get a catback system?

Gregster

[01elantra4dr]

Isnt the exhaust header and 1st catalytic converter 1 piece? If you need both cats, why dont you get a catback system?

Gregster

I thought it was 2 piece i havent looked. I just assumed since the headers come in 2 piece the stock manifold would be in 2 pieces. Haven considered that yet.

[kylemorg]

I believe that the first cat bolts onto the stock exhaust header, but you'd need a shorty header that would bolt up to the stock first cat, which I don't know if they make for the XD.

Why not start with a cat-back exhaust if you don't already have one? That way you won't have a CEL to worry about.

[mtlelantra]

Don't remember my exhaust off the top of my head but HMA shows it as one piece (not that it really means anything... it also shows the 1st oxygen sensor on the side, and mines on the front...)
http://www.hmaservice.com/GRAPHICS/ec/eckd009a.gif
You could probably get an exhaust shop to build you 2 cats into the front piping underneath the car so you'd have cat, 2nd O2 sensor, 2nd cat, and then use a catback. Or use the 2nd cat as the 1st cat, and get the shop to put in a 2nd cat where the center resonator is (or is this a fire hazard???)
But yeah, listen to those above- if you're going to need 2 cats, start with a catback...

[jrod13]

It is one piece. When I put my header on the exhaust manifold came off as one whole piece.

[KeWLKaT]

it is one piece.

its only on the early beta1's, pre 1998, that the cat and manifold were two seperate pieces.

also, the 04+ have the 02 sensor on the front

[tharptroy]

its definetely one piece

no way around losing the cat

[kylemorg]

I stand corrected.

[Vampyrate]

but is there a way to make it into a 2 piece with a little modification (of course)?

[mtlelantra]

but is there a way to make it into a 2 piece with a little modification (of course)?
You could possibly cut it and weld a flange, but why?? Even if you find a shorty header that fits, it's a lot of work to give you not that much, if any power over stock if you're going to go that way...
If you really need both cats, don't just want to catback the stock exhaust and really want a header, it'll probably be easiest to use the 2nd stock cat as the 1st cat, and then get a high flow cat as your 2nd cat mounted where the center resonator is.
You could try to mount an aftermarket cat to the end of a full header, move the flex pipe closer to the 2nd cat, but there's not a lot of room to work with at that end... take a look at the catback install DIY and you'll see what I mean, for both cases.

[Vampyrate]

would it be possible to get a cat back, say, EF, and just have someone (or DIY) a 2nd cat into it somewhere and then have room for the headers as well, or would that just be unnecessary

[mtlelantra]

would it be possible to get a cat back, say, EF, and just have someone (or DIY) a 2nd cat into it somewhere and then have room for the headers as well, or would that just be unnecessary
yeah, that's just what I said above... twice... it's the "somewhere" that you have to figure out. There's not much room in that "front" section for much of anything... You need the flexy connector in that front section so you have to find a really short cat to squeeze in there.
I'll say it again- most possibly the easiest solution if you want good headers and 2 cats is to use the stock 2nd cat as the 1st cat, and then stick another cat where the resonator of the stock exhaust was. That said, there's no guarantees that you won't throw a CEL...

[Vampyrate]

sorry, my mind wasnt with me this morning, im saying just take the cat that you have and cut and weld it right next to teh catback so it would be just 1 continous catback pretty much

[mtlelantra]

Yeah, if you really wanted to reuse the 1st cat, anything's possible. I can't really picture how you want it... I can and I can't... you want to put the 2 cats one right after the other and get essentially one long cat? Might work... 2nd O2 sensor might not like it. There's some feelings that the 2nd sensor has to be a certain distance from the 1st cat to help prevent tripping a CEL. After installing headers, using the 2nd cat as the only cat, welded a bung for the 2nd sensor that exact distance from the 2nd cat. If you leave the 2nd sensor where it is with full headers, you're guaranteed a CEL.
You're probably going to have to get a custom exhaust at any rate...
Are you sure the car won't pass without 2 cats?

[Vampyrate]

i know in VA it is impossible to do anything to the cats, if it was made with 1 it has to have 1, if it was made with 15, it has to 15.