QX70 subwoofer upgrade

[watline]

can anyone give advise on what is the best upgrade for subwoofer. Amp or Speaker or Both. What about upgrading door speakers in the backseat area?

 

[S3R3BR0]

can anyone give advise on what is the best upgrade for subwoofer. Amp or Speaker or Both. What about upgrading door speakers in the backseat area?

Here is a thread for a replacement sub and how to wire it up for the spare tire area:
Cerwin-Vega VPAS12ST Spare Tire Subwoofer


Here is some info on changing the speakers in the doors (with the bose stereo)
QX70 Upgraded OEM 6.5" Door Speakers