newbie need help on system upgrade

i'm driving an 04 Ford Escape and i'm planning to upgrade my current audio system. so any advice will do. also i live here in Philippines so any advice from my fellow audio-fanatics will surely help me.
  i have now for my headunit is an avt 6.5" double din touch screen in dash dvd player. and upfront is a 6x5 Rockford Fosgate power series two-way seperates and at the rear door is a 6x5 Peerless coaxials. in my trunk i have an audiobahn alum12n 12" subwoofer @ 1000rms dual 4-ohm and a 2-way seperates Peerless Definition 6 series. And driving my sub is a SPL 2ch 1500w amplifier and for my rockford spereates i have a SPL 800w amplifier. and powering my Peerless seperates and coaxials is a low-end China made V12 amplifier. I also hooked my system with a 3.0 farad and a Rockford Fosgate 3sixty.2 processors to compliment my underated headunit.
   i just purchased a polk momo series 6x5 2-way coaxials and i'm planning to install it upfront in kick panel. i would like to replace my 3 amplifiers, what do you think will be the best choice for it.
   and i'm planning to get another 12" audiobahn alum12n for the low freq. will it be better i would just add a 8" jl audio upfront?
   sorry for my english. thanks guys!!