Checking Your E350 & E450 For Power-Robbing Mistake

Talked with a 23 year ford tech , last 15 years in drivabilty ,he said their little trick was to remove the plastic cover that attaches to that very oval restrictive inlet piece and the other half connects over the cone filter.

If you turn it upside down it has a small drain hole for water to drain out.
He said they took a 3/4 inch hole saw and made about 4-5 more holes.
Sucks a little more air in , instead of just coming through that restrictive oval inlet section...