first of all will the 2.0L header fit on the 1.8?

also if you get a hi-flow cat after the header, would you just cut and splice wires so that the O2 sensors reach??

If you move them down the line a ways wont you have to change to heated 02 sensors? Or do we have them already, again, havent gone outside to look...

well what i was saying is if the HP Racing headers elimates the primary cat (its a two piece so you could put the cat in between the two pieces, right???) i would have to move the cat. Therefore the cat would be down futher. Also, the secondary cat is inside the silencer and we don't need that right??

If I remember correctly non-california 99s only have one cat, and that is in the header. The "silencer" is just that... Can anybody confirm?

Any pro 2001 or newer has the california exhaust with the prmary and secondary cats. This is so they'll meet that LEV crap. I've been looking for aftermarket exhausts and they all say the same thing. That the only emissions legal replacements are the cat backs that don't eliminate the second cat. And no, you can't put the stock cat in between the 2 parts of a 2 piece header. Not without some serious fabrication.

One piece vs. two piece headers...
 

It seems that the two pieces are basically like a DC Sports header or any other two piece header where the first half o f the header (4 tubes) then hit a flange and go into two tubes where the 2nd piece then runs from that flange to 1 tube where it terminates to the cat. I checked out our stock header the the primary cat is incorportated into the stock header. Yeah, it seems the sensor isse would be a problem depending on if HP Racing incorporates a sensor bung in the header. With my past experiences with headers on a Honda and Miata, stainless steel was always more expensive. Yes, cermaic coated does however have more performance value, but it's not as pretty and time consuming to make.

Maybe, the 1.8L FP and 2.0L FS are almost identical other than a 9mm crank throw difference. However they use different transaxles. I've noticed that the position of the engines in the engine bay is slightly different. That's why AEM has different intakes for the two engines, BTW. It's not much more than an inch or two, but could change where the exhaust mates to the header slightly. Yes, you would need to retain both O2 sensors to prevent a constant check engine light, and one would need to be before, and one after, the catalytic convertor.

Already have them.

No, the purpose for two piece headers is to make them easier to package and ship. The piping diameter is tuned for the application, and is the same diameter on either side of the flanges that join the two halves of the header. You would ruin the performance of the header by putting anything between the two halves. Not to mention anything the length of a cat would extend the bottom half of the header down to the ground.
Some Proteges have a secondary catalytic convertor while other have a resonator in the same area. A catalytic convertor is not contained inside a resonator (silencer), or muffler.

header
 

nopi has a header f or $173.79 4 in to 1 design. its polished and sounds good. There is a ceramic coated one for like $230, but sounds good. just thought i would share.:)

where at in the nopi site ????? little help would be nice :D

wow thats a good price for a ceramic header. I looked it up on their site but couldn't find it. do you have a link?

Just a little farther down the board
 

Re: header
 

I thought i would just share that.... THATS WHAT THIS WHOLE THREAD IS ABOUT!!!

:beer:

lol.....It still makes me laugh when i read this thread as I posted about the header like a month ago and nobody replied....LOL....