Ref.  

Free air subs aren't likely to work well in a small sealed enclosure.

keep the pioneer for free air, spenf your money on something that will be able to push in the enclosure.  free air drivers rarely have strong motors because they dont need them.  this is a result of the fact that a free air driver moves so easily anywyas that Xmax is the limiting factor, not thermal capacity.  In a fourth order box, such as the DB, a stronger motor is required because the cone is pushing against the air trapped in the back chamer, as well as pushing against the port on the vented side.  Likely a free air driver would burn out in no time if asked to perform with any authority in this enclosure.