turn the boost down perhaps? lol few twists of the actuator rod, et voila :P (make rod LONGER for less boost, this method will be ifine till u can get it setup nextmonth)

you sure its hitting overboost tho and not another problem?

must be hitting a LOT more than std boost to activate overboost on the chip

also EECIV chips have a tendancy to NOT seat very well and cause all sorts of problems, are the connectors where it plugs in all pukka and chip 100% secure? did you remove the "gunk" thats in there as std? (coz u have to)