Excuse my stupidity, but are these the screens that are supposed to prevent oil from bouncing around in the oil pan?

 

yeah that way it doesnt slosh up into the crank and bog everything down....something like that

is it true that it adds 20 horsepower?

 

when the crank is spinning it creates a vacuum. the windage tray help to keep the oil out of the fast spinning crankshaft.



think about it this way is it easier to swing your arms in the air.... or is it easier to swing them fast under water. the logical choice is in air. same goes for your engine