I do not know the CFM of the intake on these cars but I feel Oldsmobile did a good job of making the surface area of the filter area large enough to take care of the engines needs. For air flow purposes I am not sure there would be a big gain by going K&N over foam (but K&N couldn’t be worse than foam). The nice thing about the K&N is that you know it is going to seal correct. If you get the foam to thick or use to much oil on the foam then the K&N will definitely flow better. If you use the foam i would recommend using off road foam filter oil and not motor oil. The off road filter oil will not run to the bottom of the foam and filter better.
Just my thoughts on this.