This is common at stg2 as the extra airflow requires more fuel and the pump can't meet the requested amount. I find that A session on the Dyno and carefull changes to the map should sort you right out. Only stg2 stuff I don't get this issue with is when a twintake is fitted whenever I am mapping stg2 with evoms or ITG, BSH intakes I eventually hit this issue and have to back off the requested boost and requested load and add a little ignition advance to compensate. If you need any help I am always at the workshop on 01915239540Dave.