Very nice project indeed.
I guess there will also be some engine tuning involved.
In my 4/4 Sport (2009) I removed the air filter box in front of the engine and installed an open air filter system ( K&N kit nr 57-0686 for Ford Focus II) directly to the air intake at the rear of the engine via an elbow pipe together with an air ducting pipe coming from down under the radiator with an air funnel.
This modification enhances the engine breathing (I hope!), saves some weight and produces a nice induction and exhaust sound.
Cordially
D'herde Bart