All I am saying is do what you can afford if it makes you happy. I can't imagine how the vents would look good on the RS and not look good on our Foci. I would rather support someone who is going the distance on a mod (non-sticky vents) than be a guy who bashes everyone who doesn't fall within my reasoning of why a car should or should not be modded. Considering that the word on the street regarding the reason of the engine cover being discontinued is because of heat, I would imagine that letting some out might not be a bad thing.
And because, like you, I actually OWN a Focus, I can attest to the heat. I just opened my hood 3 hours after I drove it last, and it was still considerably warm. Do your thing. #justsayin