'71 Demon with 5.9 Magnum. Original '97 5.9 with new cam and 650 carb and 160 thermostat. Runs about 380 horse. Car has fiberglass sixpack hood.

Two row aluminum rad with two electric fans with shroud. Car runs ~190 in town but on the highway it will hit 230. I have a spring in the lower hose so it shouldn't be collapsing. I was wondering if the sixpack scoop could be doing this. The hood lifts about 1/2" in the back at highway speeds due to the air being forced into the scoop. Could this cause a positive pressure under the hood that would restrict air coming through the rad? Could it be the shroud restricting the air flow?

I wouldn't think this engine should have a overheating problem.