I am thinking of replacing my MTX Thunder 5000 15"sub which is in a huge 3.5cu ft vented box with a rockford RFD2215 15" DVC sub in a 2.5cu ft box vented (slightly less weight in the scoob), have any of you big sub fans any ideas on this , is it worth the change?? I am running the sub with a Kenwood 923 amp (pretty old but still has plenty of power)