Has always been high. Got a little better after adding the small ducting. Have read some forums suggesting to mount the cooler below the round frame bar. Have you got a picture of your splitter and coolers or any other info. Is the splitter legal?? What about a cooler with fans as from Summit or similiar.
Also what about getting the header heat out of the engine compartment, any ducting, header tape, ceramic coating etc used for that? I have a shield mounted on intake manifold bolt holes which helped fuel heating issue and contributed to cooler running as well.