okay, the factory H/U will be able to be used with a sub BUT....
you will need an amplifier to run the 8" sub, a cheap amp such as a Jaycar 2 x 150WRMS for around $300 will do the job, but you can get amps cheaper from perhaps strathfield.
the stock h/u will run an amp but you will need to buy a "line level to RCA adaptor" ($20 approx from marlows/jaycar/strathfield)
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