Belt was probably installed incorrectly. Take it back and have them check it.
The 2003 Subaru Legacy has a flat 4 engine.
The 2012 Subaru Legacy has a flat 4 engine.
The 2007 Subaru Legacy has a flat 4 engine.
The 2002 Subaru Legacy has a flat 4 engine.
The 2001 Subaru Legacy has a flat 4 engine.
The 2014 Subaru Legacy has a flat 4 engine.
The 2009 Subaru Legacy has a flat 4 engine.
The 2013 Subaru Legacy has a flat 4 engine.
The 2010 Subaru Legacy has a flat 4 engine.
The 2005 Subaru Legacy has a flat 4 engine.
The 2008 Subaru Legacy has a flat 4 engine.
The 2006 Subaru Legacy has a flat 4 engine.