You are absolutely correct. The mesh I used has an open area of 62.7% so it is definitely impeding airflow. However, as with anything it’s all about the trade-off's. My radiator is starting to get pretty beat up in the bottom corners so in my opinion the mesh is necessary. Also the oil coolers are very vulnerable to severe damage from being struck by large objects.
With this ducting setup my temperatures have always been very good, so I am willing to sacrafice some for saftey.
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