That G8 motor is a whole different animal than the LS's and is actually not even considered an LS at all. I had an 09 and loved it but they have some problems with the Active Fuel Management (aka Displacement on Demand) and a lot of guys just simply delete the system all together. Here is a link I had bookmarked, great info on the G8s motor:
http://www.g8board.com/forums/showthread.php?t=22509
Displacement on demand delete
https://www.texas-speed.com/p-717-do...elete-kit.aspx