A few "basic" questions. I am new to modifications and I am looking for some assistance:

I have a 98 civic Lx sedan and my exhaust manifold is cracked(hair line). My exhaust is shot and I would like to get a new Header and better exhaust. I have contacted DC sports and they tell me that they do make a header for the 98 civic lx. I was told by tech support that the ex header would make my car run poor. I have seen different people online make reference to having a DC sport header on the 98 lx. I understand the problem is the location of the cat, can I relocate it?

What do I need to do to replace the stock header with an aftermarket header? Do I need to extend the wires on the lower O2 sensor?

Also, if anyone knows what is involved, please make a recommendation on header/exhaust system for the vehicle.

Thanks, sorry if this has been answered elsewhere.