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
Injen SRI Intake. Steeda RSB