Is an amplifier needed for a woofer (for WagonR)?

Yes it will need an amplifier, the Sony XM-ZZR3301 will be a good match with that subwoofer. Wired like this ( a href="http://akamaipix.crutchfield.com/ca/learningcenter/car/subwoofer_wiring/1SVC_4-ohm_mono.jpg" rel="nofollow"http://akamaipix.crutchfield.com/ca/lear…/a )