My setup's pic is in my sig. it's exactly like illusion's old setup without the port in the box (same subs, etc). I still have about 70% of my trunk left because the box doesn't extend too far in and it's slightly tapered as it reaches the top, so i still have almost enough room for two golf bags...if i ever played golf...the shop refuses to port my box because the solo baric 15's hits hard, not loud (supposedly) but i'd really like to have it ported to get some sound out of it.

if you want sound and don't want to sacrifice space, wire a small sub inside/under your seat(s). that's what bose did a while back for mercedes benz. otherwise, ditch the spare, drop in a sub, and put some plexiglass over it.