I wondered about that myself but I planed to compendate by enlarging the boxs a bit. Unfortunatly, I overcompensated a bit too much and even with all the bracing I figure I'm still about 1000 cubic inches bigger than it the box should be. Ports are 4 3/4" diameter, 1/8 larger than design. After some listening I get a feeling that the bass is not quite right. A tad boomy in my opinion but I am not blaming anybody but myself, I'm sure Wayne's design is right on.
Good thing about it is that these speakers are my sons and he can't get enough bass. He actually turns up the bass on the tone control and then kicks the loudness button in too! I can't listen like that but as long as he is happy.
I did some listening this morning with some Vivaldi Clasical music and I gotta say that it sounded pretty darn good!
More listening and some A/B testing to come.