OP have you done Anti-Sway bars yet? I've always recommended suspension first braking second and power last. I would do sways and springs, and maybe struts if they are warrented first, then SS bake lines and a fluid swap.
Finally for more power start by swapping that BOV for a BPV (the ECU will thank you) and start looking at tubro inlets, maybe a performance Intercooler and definitely a professional tune. At that point you are at the top of a stage 2, I would start considering a new fuel pump and new injectors if you plan on making more than stage 2 power.
Just my .02c
13 WRX Hatch - Torqued Performance Stage 1+
Slow is Smooth > Smooth is Fast