If you ARE planning on upgrading your turbo, don't bother with a boost controller, just save your money for some sort of engine management later. If you DON'T plan on upgrading the turbo, then boost controller is fine. You will not have to remap anything. Just don't set it too high, maybe 15.5psi at the most.
A catless uppipe and downpipe will give some pretty big hp gains. Im not sure what the exact numbers are but i believe it too be 40-50 crank hp. You will get faster spool of the turbo and better top end. In my opinion, go with an uppipe first, followed by downpipe then some sort of catback(HKS, Greddy are my preferred choices) You don't want to put a Boost Controller until you change the uppipe. If you raise boost, it will melt the cat on the uppipe and shoot pieces of the cat in your turbo which is bad.
If im wrong in anyway here, please someone correct me.
Hope this helps