Here is what was done for a Porsche 911 racing engine.
You can see how they increased the surface area of the filter by using a convex shape.
This shape was also popular on 1960's F1 race cars although I have seen some that are almost completely spherical.
Those stacks are similar to mine. Mine have an outside diameter of 3-7/16".
The screens look similar to the "Speedmaster" ones that fit into the throats of the stacks that are stainless steel and $35 for a set of 8.
My stacks are VW dune buggy sourced. It isn't without question that the large diameter 3-7/16" pictured screens already exist...somewhere. I couldn't find any so I made mine out of stainless steel sink strainers that just needed to be trimmed down from 3-5/8" and o-ringed on.
The benefit being that they actually have greater surface area then anything else available. The external o-rings are the difficult parts to source.
