To enlarge the sweetspot has any-one ever reduced the tension away from the center of the racquet on the mains and crosses. i.e. to try and get the same power away from the center of the racquet use a lower tension. I don't know if the tension would even out when you played with it or if the strings keep their own individual tensions? Or if it's a stupid idea? The TW power ratings show a significant drop off in power at points only 2" away from center so maybe dropping tension away from centre would help - maybe 1lb per string so you may drop 6-7lb from the center to the edge of the racquet.