WOW!! Another project for Myth Busters!!!
I absolutely cannot believe that something like this is being even considered. I can't even guess how many chrome engine pieces have been sold since they became easily and cheaply available but it has to be at least in the tens of millions. I don't/wont use them but not for any overheating issues - usually the chrome top coating is so crappy parts either scratch easily or rust. Then there is the problem of oil leakage (engine and tranny pans plus valve covers) . Just think of the thousands of full dress motorcycles on the road these days.
My engine dress up items are aluminum - easy to clean, wont rust, scratches can be buffed out and seldom leak.
A correctly sized and maintained cooling system, regardless of the material the radiator is made from is an engines best friend for long and productive life.