hi there i have RFD2215 15" or Punch He2 single 4ohm the specs say 2.5 cubic feet and port size abs 4" x 8" long but i don't like the port so if anybody knows the sub or can tell how to build a slot port for that sub that would be great with the specs the box is tuned to 35hz

 

try this: www.subwoofertools.com/forum/ported-box.asp