The best way to do this is to take the speaker outputs (just the front pair) and feed them into an amp like this one from Alpine:
http://www.alpine-europe.com/content...-AMPLIFIER.htm
and let it split the frequency range - sending HF to the fronts and LF to the 2 subs you install in the rear doors.
The boring bits to this plan are:
- Opening up the dash and finding the speaker wires.
Trailing the wires to the amp and back again.
Finding the existing rear speaker wires and sending them the amp.
Fitting the amp somewhere!
Which is why I'll just settle for standard.
