Help w/ header install '00 Box 'S'

[mdimant]

I am new to this forum, and have just recieved some cheap chinese headers for my '00 S and need a bit of help with the swap. They are 304 ss & the tig welding is very good, much better than i expected. Pretty awesome for 70$ plus shipping. If they fit the flow will be greatly enhanced for sure, but I won't start w/out some good counsel from whomever. I have done my own CV boot swap by totally cleaning & rebuilding/rebooting, so I'm not a complete idiot, but the headers lack the front cats & don'tknow how to deal with that in leu of emissions, wiring & obd codes etc.
To begin with, this set has a receptacle just short of the triangular flange for what must be an o2 sensor, & other than that there are no other ports. the manifold end plate is very flat, collector is beautifully welded, & I'm good to go with a set of Harbor Freight jackstands I welded a knob & support donut onto. Pulling the cross bracing & sheer panel off / accessing area is simple & I have a Bentley book for procedure, but mainly the 'warm up' cat is what poses the challenge in my small cranium. I'm a finish carpenter & boat/car tweeker to some degree, & have just messed up enough stuff to be aware of my shortcomings. Thanks for any & all input. Martin 253-514-9002