I'd say the biggest HSU or SVS you can get would be a good start. Down the road you could always add a second one, too. If you can stretch your budget a bit, though, there is one solution that would probably knock your socks off- the Adire Rava. It's a 200 W powered sub built around a 12 Shiva driver in a sealed box. The price is $399, but that doesn't include shipping from Adire. You could buy a pair of them for $800, but you'd probably have to pay $80-$90 shipping. However, a pair of them would rock your world bigtime.