I would probably recomend replacing your amp and probably sub amp with beefier components to cut through your hemetic trunk. You could port the rear deck, but as I always prefer MORE POWER, I would do the former.
As for other components, some suggestions of brands might be helpful...
Xtant or HiFonics- High End
Precision Power or Infinity- Mid Grade
Kenwood Excelon- Good Entry Level
DynaAudio or Diamond Audio - High End
Infinity, PolkAudio, MBQuart- Mid Grade
Xtant, Hart High End
Infinity, Kicker- Mid Grade
As for speaker sizes, they may be had at crutcfield.com under "what fits my car?"