"Only" (lol!) 2K watts on my 18. I had a BL, but it got a little smelly when I (inevitably) cranked it too much. I probably didn't need all the options on the btl, but better to be safe than sorry, right?
It will be interesting to see the difference the box-size makes in spl. I am gonna do 2 18" btl's in 10 cubes net myself (right now, I've got one in a seven cube box and it slaaams!), and I was wondering how they would pound with a "smallish" box. Keep us posted! -Thx.