i have a '99 supercrew with a pioneer 5800, 2 diamond 5x7's in the front doors,and i'm about to install 6x9's in the back doors in addition to a rockford fosgate 600 watt 4-ch. amp....here's my question...i have (2) 12'' kicker subs...i will probably only install one (should i install both?) but i needed to know where i could get a good box to go under my back seat and still allow one side of the seat to flip over...AND if i should patch 2 channels of the amp to the sub(s) and then patch the other 2 to the front speakers or the back or if it makes a difference...any advice?