[Eric Coffey]

Although it's a little pricey, he could go the OEM route which is completely "plug & play".
Here's the factory kit (I am sure you can find it cheaper if you look hard enough):

DODGE CHARGER KICKER SUBWOOFER Upgrade 2006 - 2010 - eBay (item 310253591986 end time Dec-20-10 06:25:49 PST)

And the seperate components a bit cheaper:
Mopar OEM Dodge Charger Kicker Single 10" Subwoofer - eBay (item 250740123082 end time Dec-16-10 05:52:18 PST)
06 Dodge Charger SRT8 HEMI OEM Radio Subwoofer Amp - eBay (item 310256379515 end time Dec-28-10 05:14:49 PST)