i have a dc header with one 02 right before the cat my ? is can i run that one or do i have to weld another one to tha header if so any sugestions

 

You can't use the one down near the cat, the 02 sensor won't get hot enough to work correctly. You need to plug the lower one by the can and weld 2 in the stock location.

 

were is the stock location

 

I have a DC sports 4-2-1 that I had two O2 sensor bungs welded into for my B16A. If you look at the stock manifold you can get a good idea where they should be welded, two clearance issues to look out for, the A/C compressor and the front lower cross member. instead of having my sensors coming straight out and being too close to the rad fans, I had mine welded so that they point outward.
you can purchase the O2 sensor bungs from summit of jegs, then have a competent person drill and weld them onto the header mine was Heli-arch welded, its a cooler type of weld so it doesn't burn through the header, they are pretty cheaply made for how much they cost

Chris