Aftermarket Subwoofer Install

[festivus]

Looking to add some much needed bass to my factory radio. My M35 came with the most basic system, and I would like to install one of those self-contained, low profile powered subwoofers under the rear deck. I figure that location will keep it out of the way, and will also give it the best chance of getting sound into the main cabin. Has anyone checked the rear deck to see if there is a solid spot to hang a subwoofer? Any recommendations for a sub? I've seen similar units fom Boss, Kenwood, and Blaupunkt. Oh, and by the way, MERRY CHRISTMAS TO ALL!