There are aftermarket ones from mountune, PUMA Speed that work as well. K&N in not the only one out there. UK is leaps an bounds ahead of the U.S. on the Focus, but it seems like a lot new parts are popping up every week.
select Focus RS MK2
White Platinum Tricoat Metallic
2012 Ford Focus Titanium
Handling Package Nitto Motivo's
Borla Exhaust with UltraQuiet resonator
K&N X-4870. Steeda RSB