Yeah, I figured I would buy a catback, then just put my own downpipe in, or go TBE all together. I hear the AEM is a great intake. Short Ram intakes and the CObb intake tend to heatsoak, and cause the tune to run RICH
As for the O2 sensors and wideband, I think you should be fine.
Why don't you just go with the OTS map instead othe Accesstune. Don't you have to pay for those tunes anyways?