A 17" tall by 25" wide radiator is 425 Sq Inch. 50% is 212.5 Sq Inch.
A factory 17 inch fan shroud opening is 227 Sq Inch so a little less than 50% blocked.
The two 12 inch electric fans are about 226.19 Sq Inch so still a bit less than 50%.
Not enough to piss and moan about.
