well my buddy wants me to mod his sonata for some better cooling and i was thinking a cpu air duct would be a good start. anyways, he already has an xp-90 with a 92mm fan (don't know the brand). i've been reading up and found out that the duct should only lead up to the hsf and not surround it. so should it be able to touch the fan on the heatsink or not? also i've read that have a funnel design is best, like 120mm hole to 92 mm fan, having said that what would be the best material to use for the duct? also is an extra fan necessary to bring in more air or would a duct be enough?