I did that 'mod' 12 yrs ago
Removed chill grille.
Made an 'inverted V' out of coroplast and installed it in plenum
Reinstalled chill grille
Fan room air blows down and splits due to the 'inverted V' directing the airflow out into the ducts
And if you open Chill Grille vents is still blows directly Down
Airflow thru ducts and chill grille was increased....5vr cools down quite well in high temps
Dang...Missed the boat---should have patented 12 yrs ago
I could have been a millionaire
Dang, Dang, Dang