actually, not my idea. that said, i was changing oil on a 08 mercury milan 4cylinder and noticed a out of place plactic tube runnning from the top of the cooling fan to the back of the motor. well, where do you go? right over the heat shield for the top most cat. takes air from the electric fan and pumps it right down the downpipe.
i can think of doing this two ways. mod a existing piece(probably from the same vehicle...ive never seen another that i can remember pre wrx anyway) or install a small 12v fan in the space between timc and right strut tower. i have a bit of room running factory turbo/timc. around town i can see that helping push under hood temps down, but the hot side of the turbo needs to stay hot right? like blanket and shield hot? so the forced air would have to be routed past the turbo and pointed down the back side of the downpipe.
course, this could be solved with a ceramic coated and wrapped grimmspeed downpipe, which is on the list of course. just chewing on ideas whilst working away.