It's not hard if u got the money. You'll need the turbo, intercooler, exhaust down pipe and turbo exhaust manifold, upgraded pistons and seals, reinforced bores, upgraded valves. Upgraded fuel and water pumps to feed the extra demand. It would be more cost effective to just buy a 2.0 turbo engine and swap it out.
The 2013 Subaru Impreza has all wheel drive.
The 2014 Subaru Impreza has all wheel drive.
The 2002 Subaru Impreza has all wheel drive.
The 2012 Subaru Impreza has all wheel drive.
The 2008 Subaru Impreza has all wheel drive.
The 2010 Subaru Impreza has all wheel drive.
The 2009 Subaru Impreza has all wheel drive.
The 2001 Subaru Impreza has all wheel drive.
The 2011 Subaru Impreza has all wheel drive.
The 2006 Subaru Impreza has all wheel drive.
The 2005 Subaru Impreza has all wheel drive.
The 2007 Subaru Impreza has all wheel drive.