[Mike Taylor 3601]

Loosen lash on exhaust .005 rockers see if that helps, that will remove some duration to show you if that is what it is wanting,also can restrict exhaust and see if helps.
Also if have flow #'s if you haven't done so, take intake flow #'s from all lifts and average them, if new heads have same or lower average# may not make better power.
Mike Taylor 3601