Hot Rod or Chevy High Performance did a flow comparison of all the gauze filters a few months back, I don't remember the exact month either though, but it is out there.

Here are some formulas for K&N type filters. I believe these were found at the K&N website. Hope this helps.

Area = (CID * RPM) / 20839
Area = (Height - .75) * (Diameter * 3.141593)
Area = Length * Width
Height = (Area / (Diameter * 3.141593)) + .75
Diameter = (Area / (Height - 0.75)) / 3.141593
CID = (20839 * Area) / R
RPM = (20839 * Area) / CID
Width = Area / Length
Length = Area / Width


Paper Flows 57.3% of K&N
Foam Flows 42.4% of K&N

I also have a program if you are to lazy to do it on the calculator. Go to http://mywebpages.comcast.net/stevehuckisnot/freestuff.htm
and download the automotive calculator.

Sorry, no dimensional data, but in general a pressure drop across the filter shouldn't cost more than 1.5" water.  This can be pushed to 3.0", but the 1.5" should be used whenever possible.  We test air cleaners on the flow bench, but you could always instrument it in the vehicle for the most accurate result.

Now that's a number I've been after for a while. 3 inches of water is 0.7 kPa. Worst MAP (measured at the plenum) at full throttle I've ever seen is 5 kPa, in a prototype, and 2 kPa in production.

Thanks for that.

Cheers

Greg Locock