Ok some numbers...
The true area of the throttle body and other fixed induction parts is around 6,000mm2 and the best linking pipework is ripple free silicone 92mm diameter or 42 radius (I.D.) or an I.D. of 6,647.61mm2 I can achieve this easily between the throttle body and the MAF. The difficulty is the sandwich gap between the side of the radiator and the headlamp made up of two formed metal plates, the inner mounts the bonnet catch torsion spring, the outer forms a headlight mount and (as it turns out) the bonnet release cable and actuator for the release spring. The former has a raised lug securing the tail of the spring and the latter is smooth but stepped in shape. If you peer down the right hand side of your grille you will see exactly what I am on about.
I had thought it would not be a problem to remove part or all of the outer piece and replace the headlight mount without an issue but it is more structural then I had thought and the added bonnet mechanism complicates things.
Back to figures...
Unmodified the gap between these plates can accommodate a rectangular box duct 4" tall by 2" wide giving an internal measurement of 100 x 50mm and an area of 5,000mm2 this however gives a shortfall of at least 1,000mm or realistically 1,660mm2 from the ideal. Left at this it ends up no better than the stock option which is restricted to something like 4,800mm2 in the worst parts.
So what to do...?
Well there is an option to modify the bonnet spring assembly and liberate the inner metal plate but I cannot see anyone wanting to do this and risk a bonnet popping at speed for the sake of an induction!
Having removed the air box assembly there is a secondary route for a duct through the wing under the headlight brackets but over the fog light and into the grill area in the same location. You could fit a duct of around 2,500mm2 in this position. splitting to two pipes and then combining before the MAF would achieve nearly 7,500mm2 but have the added drag of more surface area.
Thoughts please.