It's all about airflow, which means that you have to make sure the air can
only go through the coolers. Use ABS or aluminum to block off all air that could pass below, above, or around the cooler.
For the hottest track days, getting a second pair of headlight rings and some plastic screening allows you to create scoops. I have coolers in both fenders, so I took the backs out of both headlight buckets.
