Best choice for extractors is Raptor unless you want to empty your wallet for a K2 set up or something like that.
You just need to wait for the next production run.
You can run high flow cats but be prepared for it to get raspy and loud. And most importantly get your car tuned for any exhaust mods otherwise you will be making more noise than actual power gains. You would need to get it tuned anyway if you are going to delete the sensors.
http://forum.liberty.asn.au/viewtopic.php?f=65&t=17262Check out Daytona's thread for a similar setup to what you have in mind (but with the sensors still in play)
http://forum.liberty.asn.au/viewtopic.php?f=16&t=29542