Soundsplinter coffee table project - been sitting on this for about 10 years....

You will see me post this exact thread on a couple other places, because all the forums have shifted around a bit over the last decade and a half and I want as much useful feedback from a diverse crowd as possible. I've been sitting on a single Soundsplinter RL-P15D4 for about a decade now, biding my time until I finally got all the parts for a build (I got the driver, then a calibrated umik1, a db meter, and then finally for my birthday last month I got a Behringer NX3000D) I've moved in between so what was a theater in a 20x20 room morphed to an upstairs 3 wall theater with a 7.1 setup that was 11x21 to about half that because I had to build a room for my mother to move in (so it is about 11x11 now). As I am short on space, I have to make a coffee table style subwoofer with a front/rear firing (I originally was going to do a sonosub). I've already had all the mdf cut for a box that is 11.3cf (320L) with a 8" port that according to WinISD should be 41.15 inches for a 16hz tune. This will fit in the longest size of the box since the external dimensions are 50.5Lx27W.25x20H. My options for the port are evidently sonotube or sewer pipe, the sewer pipe being some super thick stuff that evidently weighs 8lbs per foot. I do have a Creality CR-10 S5 though with which I can print my own (it has a print area of 20"x20"x20").

My main concerns is the ~8 inches headspace enough for airflow (considering I think I have to add around a half inch for the flare. I have seen an alternative to a regular port, which is the Polk power port design which I've seen a couple builds on but they were all before 3d printing was possible (people had to get them turned on a lathe, or use a router to round the disc, etc). So for the same tune, according to the calcs, the port length only has to be 13.215 inches. Assuming the power port works as intended, the nice thing is I can fairly easily adjust the tuning just by increasing the internal port length (which I can do by printing the tube as a threaded two piece pipe).

Any thoughts or should I just stick with a long tube and call it a day? I'm also looking to try and find a second driver, but these things are over a decade old and finding a somewhat unused one will be hard (have to post in the wanted section and see what happens).

Eventually I'll be moving the whole theater down into the basement, but that will be a whole other project (this used to be my grandparents home). It still has a dirt floor basement but for some reason there is a huge concrete walled area in the corner that has 1'3" foot thick walls that are about 4' high and about 12'x6'. If anyone has ideas for that, let me know! The family story is she hired a Polish guy to make a Russian oven and something got lost in translation...the unfortunate thing is that there is enough concrete from that to have put a floor in the whole basement....

Shango