My friend's set-up

Ok, my friend bought a 2010 jetta about a month ago, and we went to work and got his fb enclosure built. he has four 12" elf audio subs that run at 400 watts rms each. and he is wanting all one uniform brand in everything he can get. so he's wanting to buy two elf audio amps (two subs per amp). but like in my earlier posts, i have no clue on understanding the rms, ohm ratings and how they change when you wire it in the different ways. any help on which amp he needs to buy two of? the subs are.....[url]http://www.jokersaudio.com/index.php?dispatch=products.view&product_id=29805/url] and as for the page of amps.....[url]http://www.jokersaudio.com/index.php?dispatch=categories.view&category_id=185/url]. like i said, i'm completely lost on how to help him in this way. any help on what to buy and how to wire it would be appreciated more than you know! Thanks guys! Andy