The following changes were worth 25 degrees on my SC. That was just enough to get down to 250 at the track.
-Remove headlight, cutaway most of headlight bucket
-Use Home Depot roof vent
-The square section is cut round to fit inside the headlight bucket and I used 2 of the headlight mounting screws to hold it in place.
-The cone shaped section is then trimmed to route the air right to the cooler with no gaps.
-I then added a 6x4 hole in the lower valence
-Seal the bottom of the fender in front of the cooler so valence air must go through cooler and not around it.
250 isn't cool enough but I sold the car and built a more dedicated track car before trying to get it any cooler.