Actually, the wakeplate does help creat a bigger wake in the Outback. It "trims" the back of boat down into the water, creating more displacement of the water and thus a slightly larger wake for board sports. It also 'shapes' the wake, changing the ramp on the wake. For slalom ski speeds, it does nothing unless it is still trimmed for wakeboarding, then it creates quite a mess.
If you are looking to improve your slalom wake, this will do nothing. If you want a slight bit more control on your board sports wake, then it helps. It doesn't turn the Outback into a wake machine.