What GIAC and Revo need to due is a custom on-site tune such as HarmonMotive does for the WRX and EVO.
http://www.harmanmotive.com/
You should put on the headers, intake, exhaust, etc. then take it to them for a custom tune on the DYNO.
HarmanMotive takes advantages of all your bolt-on's so all the peramiters are maximized for HP gains and running solid with no hick-ups or CEL's.
My friend had a 2004 WRX with intake exhaust, larger intercooler, larger turbo, etc. it ran so rich he would shoot sparks out of the exhaust (Converter was removed too) and it ran really crappy. After his tune with them, his car gained like 20 hp and it ran just like stock NEVER any problems after the tune.
KRZ