Sorry, forgot about your cabinet space issue with regards to the port, so the 10" port probably isn't an option. (I still like the idea of dual six in ports, though, which are roughly 10% bigger than a single 8.) Many others here are running an 8 inch port and have no complaints about chuffing, so hopefully it won't be an issue. It's just a little bit disconcerting to me to see port air velocity of 34 m/s in WinISD when everybody says the "ideal" is not to go over 17 m/s. In this case the theoretical and the practical would seem to be two different things. I'm sure flaring the ends helps too.
Ido think you'll be OK with 10" of clearance on the side of box if you want to put the port there. That might simplify things greatly and prevent people from making jokes about your "smokestacks".
