Cat or no cat?

I've owned plenty of vehicles without a converter but since this is my first Mitsubishi I was just wondering if there is anything that I should watch out for. The talon exhaust I have did not come with a cat but it has an o2 sensor bung, I'm sure its going to throw a code but will that code cause the ecu to make my car run poorly or different? Would it be easier just to get an aftermarket cat? The length of the exhaust past the resonator is just long enough to reach my flex pipe so adding a cat would mean I have to cut and modify the pipe.
http://i1056.photobucket.com/albums/...ps8404e266.jpg

If you don't want it to throw a code you can add a spark plug defouler which will place the o2 sensor further away so it wont read a difference. You can buy them at autozone in the help section.

you will have to cut the talon exhaust anyway and have it extended a few inches as well in order for it to be the correct length for the galant

If you do what they both said above you should be fine. I've used the o2 method plenty of times works like a charm

I have headers no cats or foulers n no codes. O2s are screwed right in. Just saying lol.

Ok cool Ill do a little research about the foulers and I kno the exhaust pipe needs to be extended but I dont want to buy anything that I don't absolutly have to (trying to save up for rims). I'm pretty sure its the muffler end of the exhaust that needs to be longer, my main objective is to bolt the exhaust up with the 02 sensor bung where it sits now, if I was to put a cat in that means I have to cut and mess with the resonator end of the pipe and I really don't want to go that far.

Got my exhaust on. Everything went pretty smoothly, all the hangers and bends went right where they should. I went with no cat, from the resonator to the downpipe I added 44 total in. (including a new flex pipe) since the old one was shot. I deleted the down stream o2 sensor and rewired the up stream one to extend it back to the bung in the catback. I get a CEL occasionally but no ill effects. My car runs so much better imo, its very loud and raspy tho I'm going to be junking the muffler thats on it and going with magnaflow soon. I repainted the muffler with high temp black gloss paint also, pic below is before it was painted.
http://i1056.photobucket.com/albums/...ps6a6db532.jpg