I just upgraded my car from a single subwoofer to dual 10" Alpine Type-S subwoofers using a SubThump passenger side Stealthbox. Thanks Steve! Since my CD changer was mounted where the enclosure goes I had to move it to the rear wall amp rack. Here are a few pix. If you're a DIY installer this should give you an idea of whats possible if you can't afford a bunch of fancy glass work.

Amp Rack

JL Audio "Vantage" Stealthbox

SubThump Stealthbox

SubThump closeup

 

Looks nice... do you need to have them running in reverse polarity when they face eachother like that?

 

No. Doing that would result in no bass at all. My brother-in-law helped me do the install. He accidentally connected the subs out of phase. My 4202 amp's speaker connections go like this... + - - + When he connected the subs he assumed that the connections on the sub amp were the same. They are actually like this... + - + - As soon as I turned on the system I immediately knew that he had hooked them up wrong because there was nowhere near as much bass as I had with a single subwoofer.

 

Looks great. I've always liked your stereo install.