I dunno if there is drop-in sub, or if you'd want to bother with one. The reson that the aftermarket subs memebers have found require the spacer/trim ring is that the stock unit is about the SHALLOWEST sub around. Shallow == small magnet, weak basket reinforcement...Keller said:Or do all require a trim ring be made? Furthermore for those of you who have replaced the stock sub, is the stock amp up to task? Or is it lacking?