weak heater for canadian winter

Try to restrict air flow through radiator, and check to see if recirculated air setting helps instead of outside air.

Also slower fan speed may allow more heat transfer?

Totally agree that the 2014/15 heating is very weak making it unsuitable for real winter. Shame on Subaru. I've been looking into auxillary heaters but the good ones cost $$$$ and drain the battery which will damage it and the alternator. Some have used cardboard to block air to the radiator, an old and somewhat effective method of improving heating. Try covering half of the radiator with thick corrugated cardboard or insulation board with a reflective side facing the radiator.