To paint, or not to paint?

[F1BOAT33]

Does anyone have any thoughts as to painting block, heads, etc? How much would it effect the heat characteristics i.e. dissipation etc?

I understand that High Performance Mercury engines are come from the factory unpainted?????? There has to be a reason for this right?

Comments welcome.

[afr]

just like you said it dissipates heat better with no paint
you can see it if you use a pyrometer
but hp gain i would say is little if any

but shinny aluminum does look cool