General thinking would say that you cant get cancellation at subbass frequencies in the trunk of a car because reflections or multiple subs cant really sum to 180 degrees apart (or between 135deg and 225deg to be destructive). However some positions do result in what sounds like cancellation, such as having theh subbox face right up towards the front wall of the trunk with the drivers firing into the wall. However it doesnt seem that phase cancellation could be the source for this issue - anyone know what could cause this in the trunk?