I'm planning a refurb of a Bassman 2-15 cabinet, and I plan to install port tubes, rear mounted. I've identified two approaches that could work: one using four 4" ports and one using two 6" ports as shown here: The drawing illustrates how the port profiles would overlap (or not) the drivers at the front of the cabinet. The four-port option reduces my port velocity slightly, and is actually cheaper than the other, but not by much. It does, of course, involve more cutting, but that's not a big deal. Aside from those considerations, is there a clear advantage to one design over another? I'll be running up to 500 watts using a PF800 head. Thanks.