I changed my surround speakers so I had to run Audyssey again. I tried what MARI said put my VTF3-MK5 in sealed mode Q to .03. After Audyssey I checked the EQ on my Marantz SR5010 (Audyssey XT) and the bass EQ graph was mostly flat to almost 120hz.
I opened one port, changed the Q to .05 1/2.
Put on War of the Worlds, when the alien come out of the ground it's was like an earthquake.
Metallica Black CD nice clean tight bass, a little overpowering at times but still sweet.