Just to add, NO it is not just normal black paint haha
On my old R34 GTT I had my dumps and front pipe ceremic coated in black and proved the engine bay temperatures dropped by 15-"ish" degrees.
I had the cooling pro turn flow for my old R33 with basic mods: turbo back, 12psi, pods (if these even do anything), and flash tuned by toshi. Before the tune: car was laggy (maybe by 500rpms) but when the boost built up the car definitely performed better. After the tune: no lag, little bit more power but way better response and in general it does help your car stay healthy.
I'm planning to save up for a PWR intercooler for my GTR at the moment which is thicker than standard.