That's misleading to say that
That's misleading to say that the Outback with automatically be able to tow more if it comes equipped with the FA2.4 engine.
The 2.5L engine in Australia (Which is the same as the 2.5L in North America) is rated to tow 3,300LBS, it is more to do with government ratings/classifications and braking than the ability to move the trailer/boat/etc.
You can hook up a Crosstrek to A 5000LB trailer and be able to tow it, but braking would be a whole other story.