Ok, here's the deal. First, the O2 sensor: I know my CRX needs one; the CEL comes on intermittently, the ECU flashes code 1, and it failed its smog test MISERABLY. So, here's my question:

I just bought a used DCsports header, and the O2 sensor hole is waaaaay down by the cat flange. Stock CRX O2 sensor is located right up on top. Is the O2 sensor just a single wire that can be extended with a splice? Or is there a special piece that I'll need to extend the wire?

And secondly, along with needing a new O2 sensor, it needs a new catalytic converter also. Here's my question:

Should I buy a factory Honda cat? Or should I use an aftermarket high-flow unit? My CRX is autocrossed as well as daily driven. Only bolt-ons for the engine are allowed, so I'm wondering if a high-flow cat will improve anything at all. What say you? Stock size? Or go with a high-flow unit in combination with the allowed cold-air-intake, header and aftermarket exhaust (no larger than 2.25 inches)? Also, which brands of aftermarket catalytic converter (if i should use one) are good? thanks!!