Headers ($) + RB module ($) + wideband o2 sensor($) + additional wideband o2 module($) + performance muffler ($) + dyno tune($) will obviously make the most of it but the total cost is fairly high.
I was running an RB (no tune & no wbo2) but the RB shat itself, bike still runs better than stock in way of performance and fuel economy *.
If you get a hold of a set you can run it as is and add those additional bits as needed. I'm not sure about using stock muffler though.
*unless heavy with the throttle for sustained periods. This has been proven 😀