Hi guys:
recently I want to replace my header and catback...so I bought header on ebay and then I realized how stupid I was because I didnt know that my 98 civic lx got a CAT on my manifold....the problem is that I know the aftermarket header got 2 holes for o2 sensor...and I know I still need a aftermarket CAT....there are 3 questions I need experts like you guys to solve for me
(1) If I put the aftermarket header on my civic, I would need a CAT...Is the CAT going to be connect directly to the HEADER?
(2) Because I noticed that all the aftermarket header, CAT, CAT back system are all bolt on...but I noticed that my car's exhaust system is all welded together...how can I install aftermarket CAT, catback? Or the exhaust shop would figure it out for me?
(3) If I put the aftermarket headeron my car, is it going to let the check engine light on even I stick 2 O2 sensor in thoes 2 holes?

I know these questions sound stupid but I really need somebody to answer these for me...I have searched thesse info for days and dont know where to get these answers

Really really appreciate for any answers
Thanks

 

if you arereplacing the header, cat, and exhaust all the same time, then there is no need for a muffler shop and it should all bolt on.
but for it to bolt on, you need:
-anEX header, which is what you have because there is no cat alreasy built in
-an EX catalytic convertor, i recommend the magnaflow direct bolt on. street legal and high flow.
-and then the exhaust which you already have

all of these parts should just bolt together. and as for the o2 sensors. the first sensor should just plug into the side of the header. the 2nd o2 sensor will need to be extended to reach the next hole. just cut and splice some wire extensions and solder the connections and it will be good. as long as all existing sensors are still used in the correct places, there will be no codes to worry about.

also id doesnt make a difference if the old one is welded on or not as long as you are replacing everything.

 

thanks Sigracer10
I think I am going to return the LX header and then get EX header and megaflow CAT along with CAT back system
One more question....could you explain how to extend the second o2 sensor? Can I ask muffler shop to do that for me?
and if I just want to put LX header on it, can't I buy a CAT converter and weld it with LX header?( just curious, although I have read the frequent F&Q, buying the EX header would be the correct way to replace all the stuff on LX), if buying the EX header is the right way for replacement, why all ebay sellers dont mention about how to put a CAT on it if getting EX header apprantly is a better way?
Really really appreciate for any answers......really!
Thanks