The Maxupgrades, Maxconnect Kit is not compatible with the 2009 Mac Pro. I unfortunately found this out when I went to install my dual Velociraptor's. The new Mac Pro uses longer drive sleds and the kit does not work. I did get this confirmed from a Maxupgrades Representative via e-mail.
http://www.maxupgrades.com/istore/index.cfm?fuseaction=product.display&product_id=180
http://www.maxupgrades.com/istore/index.cfm?fuseaction=product.display&product_id=180