BoredSysAdmin thanks for the welcome. Long time lurker very few posts. My brother actually modeled the sub and came up with the 13.5 cu ft. box. I believe he said it would be around 15.8hz. I have a space for this sub and maybe even his brother if it is "necessary" so the size is fine. I know parts express says 6 cu ft. ported, but even under that it says optimum using bassbox pro was I believe 11.1 cu ft. So not sure why the 6cu ft was there except for a reference. I do not mind the size, weight, or time as long as the finished product works well and sounds sublime.
Being as this is my first time, I am very hopeful to have my homework done and make something to be proud of.
KEW, I went ahead and purchased the Crown xts1000. This will be made out of 3/4" birch ply. We have gone over the box a bunch of times, but it is just my brother and I, so I am very very happy to have as many eyes on as I can. The build timeframe is still a few weeks away, so any advice helps. We have all the tools, and now the parts, just have to buy the wood and get to work. Thanks for the advice so far and keep it coming!!
Don