I thought they looked round, I will have another look tomorow and take a quick pic. I just got a little exited when I saw 28 on them.
Suppose it wouldent make that much difference as I could port them myself but would save a little work, not sure what the port map is like on the 16 but I did see the 21 port map in the tuning section.

Think im going to keep the 16 and do a rolling rebuild, will have to be like that as im a little un'employed at the moment