I would think the heat is going to be coming from the heads and valve covers, which will move on up through the LIM to the UIM by touch, and also by the valve covers extreme heat sitting directly UNDER the edges of the UIM.
How to fix that problem? Bigger rad and water wetter to keep the coolant cool which will bring down those engine temps.
Although that coating sounds like it would sure look purty
Another great idea to help underhood temps is wrapping the exhaust manifolds.
I don't think theres much else you can do.
Oh, a CAI w/ heatsheild would probably help alot. IIRC, Stazi said that the vents in his hood kept his UIM so much cooler because the underhood heat was vented out, and the filter was getting cool air in, which kept the UIM cool.
