To reduce underhood temperatures, try removing the weather stripping that is on the cowling just below the windshield. This will allow more air to flow over the top of the engine and evacuate more hot air from the engine bay. If you still want more cooling you can put washers in between the hood hinge bracket and the hood, this will raise the back of the hood making a larger gap in between the cowling and hood, allowing even more air to exit the engine bay.