Don't think Drews ever ran 2.1 in the wagon. If 400 is you final goal, 2.0 will be fine with the correct supporting mods, it won't be cheap though once you figure in.
Forged block
injectors
uprated pump
turbo
ecu + map
Some decent brakes
Just for starters.
My opinions is save up & by a car already done, it would work out alot cheaper.