I'm still waiting on my Corbeau brackets. Hopefully it'll be here soon.
As for the airbag light, the fix for the WRX was a 3.3 ohm resister plugged into the harness to fool the computer into thinking the airbags are there. I haven't tried it yet on the STi, but it'll probably work. If not I'll just have to measure the resistance on the seat with a multimeter.