Sorry I jsut read the post that said FSWERKS is where you got your tuner. Call Randy at fswerks and tell him you need a tune to disable your rear o2 sensor for your header. The tune is only $35 since you already purchased a sct from them. He will modify the tune for you and send you the file in an email. You then connect your sct to your computer to download the new tune to your flasher and then install it on your car.
So here is a list of things your need to purchase at once from them:
Fswerks Stealth front pipe-$150
That is the complete list of things you need to install the header(=
Then if you want it quieter you can add mufflers after that.