actually, you want the outtake removing air at the same or higher rate as the intake. You want to remove the warm air from the components. If you wanna try this test and dont mind ruining a perfectly good system, set all fans as intake. Get very stale, hot air. Now all as outies, you still get high temps but the fans are pulling the hot air AWAY from the components. Now for maximum effect, pull the hot air away in equal or greater amounts pcf than the intakes, then you get the heat away from the components, and good air convection. As far as the placement, depends on what you have and case types as well as heat sinks, but for the most part, yeah you want to try and suck through the top if possible, but may not be depending on the hardware, but above all that make SURE to keep the air flow in ONE general direction and no cross flow.