i bought a megan racing header, and no name downpipe for my 02 DX. question about the downpipe though. can i get a magnaflow catalytic converter welded into the downpipe, and the downstream o2 sensor would just go into the cat? heres a pic, any help is appreciated. thanks!

 

ya im sure you could weld it right up to it...
just ensure that the pipe will fit on the exaust first, then see if the cat converter will fit in that location... then cut the downpipes and if you need to use some adaptors to fit the pipe and the cat converter.... and weld it all up. would be BEST if you had a welder to bolt the setup onto the car and then a few tack welds on the setup to ensure the perfect fit then unbolt it and weld it up on a bench....

not sure HOW your sensor is setup from factory or in the cat..... but if you go to a exaust shop you can buy a O2 bung and then just cut a hole into the pipe where ya want it and weld it in...
and after youve done all your welds use some hightemp primer and some hightemp paint over the welds to ensure they wont rust out so easy.....

 

ok cool man thanks. what do you mean by o2 bung? like the upstream o2 sensor wil go right into the header, but hte downstream i will have to extend the wires to wherever the cat is welded.

 

well what im talking about is a O2 bung that is like a circle with threads for your O2 sensor..... would be BEST to take them your O2 sensor so they get the right threads.... yes thier is a difference...

the one i got also had a plug for it. so i put it in my other unused O2 sensor location...

now im not sure HOW your exaust setup is from stock.....
tho with extending the wires that can be iffy.... i tried with my header cause my header didnt have the O2 sensor location in the rear... soldered some wires same gauge as on the sensor BUT i dont know what was up..... cause as soon as i turned the key over the CEL light came on which is why i had to end up welding in another O2bung and then had to unsolder those extension wires and solder them back together..... and now i dont have the CEL light....

so definatly cross your fingers if ya move the sensor any.... or the wires.. ive heard some people do it just fine without any problems, but for somereason i didnt have that luck

 

yeah. well see at the front of that downpipe, there is a hole for an o2 sensor. do you think if i got the cat welded in and put the o2 sensor in that hole instead of the cat, would i still pull a CEL?

 

so i talked to the service manager here at western honda, and he said if i dont get the cat welded on, basically just throw the downstream o2 sensor away cuz im gunna pull a CEL anyway, but if i do get it then the downstream either goes after the cat or at the very end of the cat. does that make sense?

 

so wheres the factory cat at?

 

its built right into the bottom of the exhaust manifold, il see if i can find a pic. but he said i can extend them with normal copper wire so i will just get a thing drilled/put into to very end of the magnaflow catalytic converter i bought, then put the downstream o2 sensor there. hopefully everything will work and no CEL haha. il let you know how it goes once i get it on! thanks for your help addiction

 

^ yeah what you said should work, but are you removing the stock cat in the exhaust manifold? Idk why you'd need two cats lol unless you are putting a header on there

 

yeah man at the top it says i bought a megan header and regular downpipe haha so im ditchin the stock exhaust manibut yeah im really excited to get everything on, i also have a pulley system coming and a throttle body spacer (i only got it cuz my friend sold it to me cheap) so yeah should be interesting, and im starting my body work -> paint job in december, should be a decent car after winter!