Reading K&N's website:
K&N Air Filter Facts You Should Know
Their formula (don't know where this comes from...) is:
Required Filter Surface Area = (displacement in cubic inches * RPM at max power)/20839
All the engines use the same filter? So the biggest demand for air is the 3.2 V6 (194 cubic inch), peak power at 6200 rpm.
Solution to the formula above = 57.72 (this is in square inches, damn Americans...)
Or in metric: 372 cm^2
So the GTV filter is a cylinder, 14.5 cm outside diameter, 23.5 cm length. Simple maths says the outside surface area of this filter is:
A = 14.5 * 3.141 * 23.5 = 1071 cm^2
So my conclusion is that the OEM sized filter, regardless of material type has around 3 times the surface area required
for the biggest engine! According to K&N's rekoning:
Originally Posted by K&N
Keep in mind, this is the minimum size requirement. To extend the service interval and to provide an even greater volume of air to the engine, install the largest filter that will fit in the space allotted.
Any errors in my maths? its late.
Edit: yes there was a pretty big error......... corrected it now!