Just so you guys know where I got that an xp3000 would be good for 3000 watts was in page 6 of the group buy thread where scottie posted this:
"Choosing which XP series battery to use is made fast and easy by referring to the part number. The model number is the wattage recommendation, so for example, if you have a 750W system, you should add the XP750 to your existing charging system. If you have a 2,000W system, choose the XP2000. If you are building a massive ground pounder with 30kW, you need 10 x XP3000's. If you want to add more capacity so it can play for extended periods of time, then add more as needed to create the desired capacity. It never hurts to have more capacity than needed... the more battery power you have, the higher your voltage will stay under load, and the louder your system will play."
http://www.stevemeadedesigns.com/board/topic/132241-xs-poweraudio-savings-smd-group-buy-2012/page__st__100