On my Stadium II, powercord upgrades made a very noticeable improvement. I have tried several and am now using the Analysis Plus with the Wattagate connectors to good effect. Placing the sub on a hard surface with Black Diamond Racing Cones/Pits against the cabinet bottom made a remarkable improvement in transient speed and detail. Also, a Sumiko guy recommended placing a bag of lead shot on the cabinet top to damp cabinet expansion, which makes the sub quicker in my system.