Your only real options are Phase 1 OBD2 and piggy back, or Phase 2 with WRX wiring merge. Both routes require some wiring know how. Neither is impossible or really even difficult. It is more time consuming then anything. My 98 Leggy passed AZ inspection/scan running ej255 short block, EJ25d massaged heads, 550 injectors, and Emanage ultimate. As long as you dont live in the socialist republic of cali, you should be fine!

I would recommend doing a phase 2 WRX harness and tuning with opensource/tactrix/accessport whatever, as it gives you more options down the road.