cat question
 

i just installed my megan racing header today but didn't put a converter on it yet. I have a magnaflow high flow converter but its 3" inlet/outlet. Would it be a bad idea to just use reducers to my 2" exhaust since the cat is designed for more exhaust flow? I really dont want to have to buy one. Im trying to save up just to get it all welded together. lol. thanks

It should be fine.

A couple of related questions, and a recommendation:
Is your exhaust currently all bolted together, or is it welded together?

Since you have a DX, is there a section of the exhaust pipe directly after the header that is about 18 1/2" long, and then another flange? (Assuming you have an aftermarket exhaust)

If the answers to both of these questions are yes, I would recommend getting a 96-00 Civic EX (it will fit your DX if you have that 18 1/2" section I mentioned) Magnaflow Direct-fit exhaust from summitracing.com and just selling the universal one you have. The direct-fit one is still high-flow, but it bolts together with no welding required. It just replaces that 18 1/2 inch section of exhaust (that could also be referred to as a test pipe). This way if you ever need to mess with it again it will be simple, and you don't have to get it installed, you can do it easily yourself (it's only 5 bolts). Another thing about the direct-fit cat is it has a spin flange which will help with exhaust alignment underneath the car, and will take stress off the midway flange on your header that can cause a bad seal at the midway flange (I mentioned this in a response to your post in the "What have you done to your civic today" thread.) I have a Megan Racing Header, and I know about the alignment issues you may have run into when bolting it up the the exhaust. The spin-flange will help with that. I have one of the Magnaflow Direct-fit catalytic converters and I love it because of this.

If you choose to follow this route, selling your universal catalytic converter should be easy since it's universal. I'd just put it on ebay as buy-it-now for a price just slightly lower than most online stores, so that you get most of your money back from it and so that it sells easy.

Another thing:
You know you are going to have to get an oxygen sensor extender to get it to reach down to its new location after the catalytic converter, right?

thanks for all the advice and help. My exhaust is all bolted together. Its pretty home-made. lol. I have a female flange after the header and 2" pipe back to the pipe that curves and then goes back to 2" to the muffler. I am probably just going to have my cat welded on and have the rest of the exhaust welded as well. I put on a few extra exhaust hangers so there really isn't much stress on the midway flange. i did take that into consideration when putting it all together. What I did for the oxygen sensor is just re route the one plug in over the back of the trans and that worked fine for me.
i appreciate all the help
-Matt

alright
then yea, since you've already taken care of the possible problems then i would definitely just use the universal cat as you have planned
the main reason i recommended the direct fit cat is actually because of the reason i bought it: my exhaust was poorly aligned underneath my car, and rattled against the fuel tank, and hung too low. I tried adjusting it, and using polyurethane hangers, and no luck. The spin flange allowed me to twist my exhaust in the appropriate direction, and it no longer had fitment issues and there is no longer stress on the midway flange.

yeah mine has an occasional vibration against one of the heat shields but i can put up with it

if you decide that it bothers you, you can just remove the heat shield.
it's only a couple of 10mm (i think) bolts.
it helps to have rachet wrenches