From my experience the Qts is way too high and 8 woofers way too many. Use one high-quality mid on each side - get out of it between 100 and 200Hz and you'll have no problems with excursion or bass.Be prepared to eq it.
Check out Dick Olsher's design for something that works very well. I've built 4 or 5 versions and all of them were very good except for SPL - mid driver would bottom out at "movie" levels or really wide dynamic range recordings.