need advise on setup, 03 silverado

hey guys im starting a project on my 03 silverado extended cab, i am going to do a three 12" set up two under the back seat and one under a center console im also building im going to run an amp for both the speakers in the back and a separate amp for the middle speaker. my conscern right now is that if i build the box with the speakers downfireing or the speakers facing the top to the seat what do you guys think will sound better? im going for clear balanced sound not more bass or more midds or highs i want everything to be at the same vol. but when i need to crank it up  i wana be able to just flip the amp for the third speaker on and get more also im installing screeans in the headrest if anybody  has any tips on those i would apreciate it. also in the middle console im putting one screen in the back, a ps2, dvd player and equaliser also on the 03 silverado you have a small console you can say on the roof right by the rear view miror im going to customise it to fit a 6" screen to hook up with a back up camara im doing both the box and console out of mdf and wrap them in vinyl matching my interior

any sugestions will be considerated please feel free to coment 

Nice start, i think firing down would be better if you dynomat the entire floor cuz it'll all bounce off....Post pics when you start...good luuck