Two Alpine type -r's (12"4ohm) or One Alpine type-x (12")?
Good choice in amps, that amp is a monster and will push anything really well. Also, i would just go with the one type x 12" sub. If you put it in a good ported enclosure it will be a real nice system. Good Luck!!! Edit: Yes, 5x7 and 6x8 are usually ...
GTO1204BP-D or Polk db212-2? With which Amplifier?
The Alpine PDX 1.1600 is the best. Don't settle for anything less. I know, I am a stereo expert.
alpine or pioneer?
Alpine is far superior to pioneer, as far as im concerned not including the high end stuff alpine is the shit!. i own a new alpine head unit and it sounds awesome has good features and it cranks way louder than my buddys pioneer.