Despite all the extra wiring I did, that is what I have: a subwoofer amplifier combo or a Powered Subwoofer.
Rockford fostgate makes a 10 inch powered that fits perfectly in the spare tire hole (mine is a 12). There are also even smaller ones you can mount under your seat
But, once you start wiring, you may find its not much less work without a separate amp, just less wires and possible mess.
I bought mine for $180 from Sonic Electronix. 60 day returns, 1 year warranty
There are also low pitch bass speakers you can replace the rear door speakers with, it wasn't enough for me, but it was substantial.






