I recomend on the other side, for the O2 sensor. Oldsman are you having any problems with that setup? the down pipe idea is giving me a nightmares, I re-doing the whole thing when I a job.
You could do it yourself if you have the following:
1. a lift
2. a MIG welder w/ SS wire.
3. a pipe bender
4. a pipe expander/reducer
and a few other things
What I plan on running is the OBX header, unless I can aford Stan's, pacesetter is poop, the ID flex pipe, and my catco cat. all 2.5" from the down pipe to the 2.25 mandrel bent borla. Oh yeah that will give me a full stainless setup (if I use the OBX) from the head to the tips
Anyway you slice it your looking at about 350-400 installed for most headers.