Hi everyone, this is my first time posting here so please help out. I have a 1997 Civic DX, engine code D16Y7. I wanna change the header on it with a Megan Racing one that I can get a good deal on, but my car is the one that has the stupid CAT built into the header right at the exhaust manifold. Now I know moving the stock location of the CAT is illegal here in Ontario, but that is not my concern, cause no one knows where it is suppose to be anyways. My concern is will I still be able to pass emissions if I put an aftermarket CAT into the mid section right after the header??? My car is an OBDII, so now O2 sensor position is key, cause from the factory there is one right before, and right after the CAT (in the actual bottom of the CAT). If I put the one in the top where it is suppose to be on the new header, and then buy an aftermarket CAT with the second sensor in it or get an Integra CAT (I heard this could work) and put it in the midsection, do you think I'll run into problems??? Will the O2 sensores be in wrong spots to work properly and make my engine light come on and send bad info the the ECU or something??? I know the Megan Racing header has 2 premaid holes on it, one at the top, and one right at the bottom of the header, but if you use these two holes, things cant work properly cause both the sensors would be before the CAT and that defeats the purpose of OBDII. Has anyone else had this problem or know exactly what to do??? Honda suggested the Integra CAT or getting the computer chipped afterwords. Please help! haha
thanks, Anto.

 

You can run your header and put a cat on for legal and health issues. What I would do about the O2 sensor location, is just use the bungs in the header, put your O2 sensor in the first one and run an O2 simulator in the other. It sends a signal to the ECU to trick it to think everything is fine. Just search "O2 simulator" and something will come up, they are like 25 bux...I'm busy right now or else I would put the link...maybe later if you can't find it.

 

you're not gaining anything with that header FYI

 

Get one of these stock mid pipes and stock cats, reuse your stock axleback, and extend your secondary O2 sensor so that it can reach the cat. Everything will bolt up perfectly. I did this to my 99 DX hb. I used a stock 00 Ex header, stock 00 Si cat, and stock 95 Ex mid pipe. No modifying needed at all. Another route you can go with which may be cheaper is to get one of the cats mentioned below and have a muffler shop cut your exhaust mid pipe and weld a 3 bolt flange on it so the cat can fit under there.

Stock mid pipe from:
92-00 Ex coupe
92-95 Si hb

Stock cat from:
96-00 Ex coupe
99-00 Si coupe

 

you guys are a great help, I appreciate all your comments.

I have looked into the O2 simulator and I am really thinking about doing that, it looks really easy.

but on another note, the EX civics do not have the stock CAT located in the header at all??? is it in the mid pipe by the resonator? cause if so, then I definitely could just get my hands on one of those and bolt it right in and then extend the secondary O2 sensor to plug into the back of that CAT. that would be really easy and I wouldnt have to visit the muffler shop.
also, does anyone think I will benefit from replacing the header? I have read you can gain like 10-15HP if you change the header and upgrade the rest of the exhaust (bigger piping)... its probably a bunch of bs, but I am curious.

anymore info on changing the header and the stupid O2 sensors and where they should be located so I don't run into CEL problems is greatly appreciated!

thanks, Anto

PS. check out my ride on my cardomain site and let me know what you guys think!

 

You would be lucky to see a 5 whp gain across the powerband....and on that motor I doubt even that much. As far as the o2 sensor....you'll need to add one and run the wiring to it, plus you'll need a new cat and exhaust pipe. Not really worth the money you'll spend IMHO.

 

I'm waitng on a recently shipped DC 4-2-1 D series header to arrive so I can replace the stock D16y7 header. I plan to use the stock bung location on the DC header for the primary sensor and have sourced a cat from an EX civic that I plan to have welded onto the B-pipe after the header. I'll hook the secondary O2 into the cat.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xEnderx &raquo;</TD></TR><TR><TD CLASS="quote">you'll need to add one and run the wiring to it, plus you'll need a new cat and exhaust pipe. Not really worth the money you'll spend IMHO.</TD></TR></TABLE>

I got all of the above for $50. If $50 is alot to you, you are in the wrong place.