Since this is active again, I'll update. I built the box as I designed and it came out good except I f()cked up the speaker holes. boo.
I've redesigned the box w/a higher tune and slightly smaller and it'll be more straight forward.
Figuring out the box tune by speaker movement I think the orig. box came out tuned to between 30-32. I feel like its not quite as punchy w/rock as my 36Hz box for my 8's was, so
with the next box I'm tuning to 35 which is SD's recommendation anyway.
3.5 cubes at 35 Hz