FWIW - using the KN formula..the following applies...

A 408 spinning to 6500rpm requires 127sq" of filter surace area.

The formula is (rpmxcui) / 20,839.

Using a circle calculator - circumferance x height.

the following cam be calculated....

Your 14x3 cleaner without xtreme lid offers 131.94 sq" of surface area

A 9x5 offers 141.35 sq"

and an 8x9 provides 226 sq" of filter area.