I am using the 4th expansion slot so that I get a slot in between for air.
I just came across a post on another forum where a member removed the drive cage to fit a pump. http://forum.lowyat.net/topic/1355425
You are likely to cut out your dvd drives if you do that too, there is already barely enough place there (main bad thing of the ft02), you can look at this pic to see what I mean, the only way id see it work is without the gap.....